Repurchase Agreements Repurchase Agreements By Maturity Period (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Deferred Costs	$ 243	$ 659
Maturity up to 30 days [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	206,112	622,957
Maturity 31 to 60 days [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	492,145	1,263,105
Matuity 61 to 90 days [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	665,020	298,660
Maturity 91 to 120 days [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	783,371	1,092,681
Maturity 121 to 190 days [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	1,434,349	287,384
Repurchase Agreements [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements, Maturities	$ 3,580,997	$ 3,564,787