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

Repurchase Agreements Schedule of Repurchase Agreements by Maturity (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	$ 12,624,510	$ 6,660,148
Maturity up to 30 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	3,038,229	1,967,009
Maturity 30 to 59 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	3,528,393	1,263,060
Maturity 60 to 89 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	1,731,595	1,096,410
Maturity 90 to 119 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	849,621	359,171
Maturity 120 to 364 days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	2,279,172	923,248
Maturity on Demand [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	997,500	1,001,250
Maturity Over One Year [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets Sold under Agreements to Repurchase, Repurchase Liability	$ 200,000	$ 50,000