Annual report pursuant to Section 13 and 15(d)

Schedule of Repurchase Agreements by Maturity (Details)

v3.3.1.900
Schedule of Repurchase Agreements by Maturity (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 5,008,274 $ 12,932,463
Assets Sold under Agreements to Repurchase, Interest Rate 1.10% 0.64%
Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 2,689,363 $ 3,979,317
Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 1,739,237 4,595,425
Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 161,449 903,286
Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 175,486 434,550
Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 242,739 1,929,164
Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   997,500
Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 93,221
US Treasury Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   $ 1,996,250
Assets Sold under Agreements to Repurchase, Interest Rate   0.23%
US Treasury Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   $ 998,750
US Treasury Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Treasury Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Treasury Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Treasury Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Treasury Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   997,500
US Treasury Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Government Agencies Debt Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 3,337,710 $ 8,458,572
Assets Sold under Agreements to Repurchase, Interest Rate 0.65% 0.42%
US Government Agencies Debt Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 1,719,292 $ 2,305,726
US Government Agencies Debt Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 1,407,353 3,568,049
US Government Agencies Debt Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 143,051 631,992
US Government Agencies Debt Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 68,014 317,155
US Government Agencies Debt Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 1,635,650
US Government Agencies Debt Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
US Government Agencies Debt Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 1,480,182 $ 2,324,395
Assets Sold under Agreements to Repurchase, Interest Rate 2.03% 1.79%
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 852,436 $ 630,118
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 271,819 945,032
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 15,691 260,228
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 106,007 117,395
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 234,229 278,401
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   93,221
Inverse Interest-Only Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 122,523 $ 138,133
Assets Sold under Agreements to Repurchase, Interest Rate 1.18% 0.99%
Inverse Interest-Only Securities [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 58,286 $ 44,723
Inverse Interest-Only Securities [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 60,065 82,344
Inverse Interest-Only Securities [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 2,707 11,066
Inverse Interest-Only Securities [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 1,465 0
Inverse Interest-Only Securities [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 0
Inverse Interest-Only Securities [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
Inverse Interest-Only Securities [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
Loans Held-for-Sale, Residential Mortgages [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 8,510 $ 15,113
Assets Sold under Agreements to Repurchase, Interest Rate 2.87% 3.03%
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 0 $ 0
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 0
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 0
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0 0
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 8,510 15,113
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity on Demand [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   0
Loans Held-for-Sale, Residential Mortgages [Member] | Maturity Over One Year [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements   $ 0
Commercial Real Estate Assets [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 59,349  
Assets Sold under Agreements to Repurchase, Interest Rate 2.62%  
Commercial Real Estate Assets [Member] | Maturity up to 30 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 59,349  
Commercial Real Estate Assets [Member] | Maturity 30 to 59 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0  
Commercial Real Estate Assets [Member] | Maturity 60 to 89 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0  
Commercial Real Estate Assets [Member] | Maturity 90 to 119 Days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements 0  
Commercial Real Estate Assets [Member] | Maturity 120 to 364 days [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Repurchase agreements $ 0