Quarterly report pursuant to Section 13 or 15(d)

Schedule of Repurchase Agreements by Maturity (Details)

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Schedule of Repurchase Agreements by Maturity (Details) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 0.75% 0.64%
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 9,422,803 $ 12,932,463
Assets Sold under Agreements to Repurchase, Weighted Average Borrowing Rate, Excluding U.S. Treasuries and Interest Rate Swaps 0.75% 0.72%
Assets Sold under Agreements to Repurchase, Weighted Average Remaining Maturity, Excluding U.S. Treasuries and Interest Rate Swaps 69 64
Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 2,453,972 $ 3,979,317
Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 3,624,004 4,595,425
Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 715,240 903,286
Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 535,472 434,550
Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 2,094,115 1,929,164
Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   997,500
Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 93,221
US Treasury Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate   0.23%
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 1,996,250
US Treasury Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   998,750
US Treasury Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
US Treasury Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
US Treasury Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
US Treasury Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
US Treasury Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   997,500
US Treasury Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 0
US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 0.45% 0.42%
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 7,321,300 $ 8,458,572
US Government Agencies Debt Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 1,912,119 2,305,726
US Government Agencies Debt Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 3,077,003 3,568,049
US Government Agencies Debt Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 484,627 631,992
US Government Agencies Debt Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 471,052 317,155
US Government Agencies Debt Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 1,376,499 1,635,650
US Government Agencies Debt Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
US Government Agencies Debt Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 0
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 1.85% 1.79%
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 1,936,232 $ 2,324,395
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 471,133 630,118
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 461,904 945,032
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 230,613 260,228
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 64,420 117,395
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 708,162 278,401
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 93,221
Inverse Interest-Only Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 1.03% 0.99%
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 132,867 $ 138,133
Inverse Interest-Only Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 47,770 44,723
Inverse Interest-Only Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 85,097 82,344
Inverse Interest-Only Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 11,066
Inverse Interest-Only Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 0
Inverse Interest-Only Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 0 0
Inverse Interest-Only Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
Inverse Interest-Only Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 0
Loans Held-for-sale, Mortgages [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 2.63% 3.03%
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 9,454 $ 15,113
Loans Held-for-sale, Mortgages [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 0
Loans Held-for-sale, Mortgages [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 0
Loans Held-for-sale, Mortgages [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 0
Loans Held-for-sale, Mortgages [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0 0
Loans Held-for-sale, Mortgages [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 9,454 15,113
Loans Held-for-sale, Mortgages [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   0
Loans Held-for-sale, Mortgages [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability   $ 0
Loans Held-for-investment, Commercial Real Estate [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Interest Rate 1.84%  
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 22,950  
Loans Held-for-investment, Commercial Real Estate [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 22,950  
Loans Held-for-investment, Commercial Real Estate [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0  
Loans Held-for-investment, Commercial Real Estate [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0  
Loans Held-for-investment, Commercial Real Estate [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability 0  
Loans Held-for-investment, Commercial Real Estate [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Repurchase Liability $ 0