Derivatives and Hedging Activity (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Credit-risk-related Contingent Features
Ratio of indebtedness to total assets above which will the Company could be declared in default (as a percent)	75.00%
Derivatives in net liability position	$ 17,200,000
Collateral posted	5,200,000
Termination liability value	17,200,000
Interest rate contracts | Derivatives not designated as hedging instruments
Gain loss derivative instruments
Realized gains (losses)	(15,843,000)	(1,630,000)
Unrealized gains (losses)	(11,287,000)	(55,000)
Foreign exchange contracts | Derivatives not designated as hedging instruments
Gain loss derivative instruments
Realized gains (losses)	(1,264,000)	(117,000)
Unrealized gains (losses)	5,755,000	(7,383,000)
Credit spread derivatives | Derivatives not designated as hedging instruments
Gain loss derivative instruments
Realized gains (losses)	2,358,000
Cash flow hedges | Interest rate contracts
Gain loss derivative instruments
Amount of loss recognized in OCI on derivative (effective portion)	1,951,000	3,367,000
Amount of loss reclassified from accumulated OCI into income (effective portion)	2,113,000	1,742,000
Amount of gain recognized in income on derivative (ineffective portion)	$ 45,000	$ 46,000