Derivatives and Hedging Activities Derivatives and Hedging Activities (Details 3) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	$ 2,651	$ 69	$ 85
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	2,651	69	85
offseting disclosure, netting adjustment, derivative liability, fair value	(2,677)	(69)	(85)
offsetting disclosure, collateral value, derivative asset	26	0	0
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	61,839	77,839	84,860
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	61,839	77,839	84,860
offseting disclosure, netting adjustment, derivative asset, fair value	(2,677)	(69)	(85)
offsetting disclosure, collateral value, derivative liability	(59,162)	(77,770)	(84,775)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
Designated as Hedging Instrument | Interest Rate Swap
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative liability, fair value, gross	13,289	19,080	22,071
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	13,289	19,080	22,071
offseting disclosure, netting adjustment, derivative asset, fair value	0	0	0
offsetting disclosure, collateral value, derivative liability	(13,289)	(19,080)	(22,071)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
Not Designated as Hedging Instrument | Interest Rate Swap
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	2,585	55	63
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	2,585	55	63
offseting disclosure, netting adjustment, derivative liability, fair value	(2,585)	(55)	(63)
offsetting disclosure, collateral value, derivative asset	0	0	0
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	48,458	58,714	62,733
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	48,458	58,714	62,733
offseting disclosure, netting adjustment, derivative asset, fair value	(2,585)	(55)	(63)
offsetting disclosure, collateral value, derivative liability	(45,873)	(58,659)	(62,670)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
Not Designated as Hedging Instrument | Foreign Exchange Contract
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	66	14	22
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	66	14	22
offseting disclosure, netting adjustment, derivative liability, fair value	(92)	(14)	(22)
offsetting disclosure, collateral value, derivative asset	26	0	0
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	92	45	56
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	92	45	56
offseting disclosure, netting adjustment, derivative asset, fair value	(92)	(14)	(22)
offsetting disclosure, collateral value, derivative liability	0	(31)	(34)
offsetting disclosure, net amount total, derivative liability, fair value	$ 0	$ 0	$ 0