Derivatives and Hedging Activities Derivatives and Hedging Activities (Details 3) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	$ 3,063	$ 69	$ 148
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	59,135	77,839	84,459
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	59,135	77,839	84,459
offseting disclosure, netting adjustment, derivative asset, fair value	(3,032)	(69)	(121)
offsetting disclosure, collateral value, derivative liability	(56,103)	(77,770)	(84,338)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	3,063	69	148
offseting disclosure, netting adjustment, derivative liability, fair value	(3,032)	(69)	(121)
offsetting disclosure, collateral value, derivative asset	(31)	0	(27)
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative liability, fair value, gross	14,319	19,080	23,229
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	14,319	19,080	23,229
offseting disclosure, netting adjustment, derivative asset, fair value	0	0	0
offsetting disclosure, collateral value, derivative liability	(14,319)	(19,080)	(23,229)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	3,010	55	105
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	44,794	58,714	61,214
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	44,794	58,714	61,214
offseting disclosure, netting adjustment, derivative asset, fair value	(3,010)	(55)	(105)
offsetting disclosure, collateral value, derivative liability	(41,784)	(58,659)	(61,109)
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	3,010	55	105
offseting disclosure, netting adjustment, derivative liability, fair value	(3,010)	(55)	(105)
offsetting disclosure, collateral value, derivative asset	0	0	0
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	53	14	43
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	22	45	16
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	22	45	16
offseting disclosure, netting adjustment, derivative asset, fair value	(22)	(14)	(16)
offsetting disclosure, collateral value, derivative liability	0	(31)	0
offsetting disclosure, net amount total, derivative liability, fair value	0	0	0
offsetting disclosure, offset amount, derivative liability, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative asset, falir value	53	14	43
offseting disclosure, netting adjustment, derivative liability, fair value	(22)	(14)	(16)
offsetting disclosure, collateral value, derivative asset	$ (31)	$ 0	$ (27)