TWO Annual report pursuant to Section 13 and 15(d)

Schedule of Repurchase Agreements by Collateral Type (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 12,932,463	$ 12,250,450
Assets Sold under Agreements to Repurchase, Interest Rate	0.64%	0.69%
US Treasury Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	1,996,250	997,500
Assets Sold under Agreements to Repurchase, Interest Rate	0.23%	0.03%
US Government Agencies Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	8,458,572	9,109,510
Assets Sold under Agreements to Repurchase, Interest Rate	0.42%	0.46%
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	2,324,395	1,829,709
Assets Sold under Agreements to Repurchase, Interest Rate	1.79%	2.01%
Inverse Interest-Only Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	138,133	166,438
Assets Sold under Agreements to Repurchase, Interest Rate	0.99%	1.05%
Loans Held-for-sale, Mortgages [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 15,113	$ 147,293
Assets Sold under Agreements to Repurchase, Interest Rate	3.03%	2.85%