Schedule of Location of Derivatives on Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Interest rate swap asset	$ 15,841
Forward purchase commitments - Asset Derivatives found in Other Assets		5,452
Futures contracts - Asset Derivatives found in Other Assets	11,148
Interest rate swap liability	125,133	243,945
Futures contracts - Asset Derivatives found in Futures contract liability	36,733
Forward purchase commitments - Asset Derivatives found in Other liabilities	$ 5,741