Derivatives and Hedging Activities Derivatives and Hedging Activities (Details 3) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	$ 54,695	$ 58,831	$ 56,401
offsetting disclosure, total gross amount not offset, derivative asset	54,695	58,831	56,401
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	71,933	77,906	80,174
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	71,933	77,906	80,174
offseting disclosure, netting adjustment, derivative asset, fair value	(59)	(69)	(228)
offsetting disclosure, collateral value, derivative liability	71,992	77,975	80,402
offsetting disclosure, total gross amount not offset, derivative liability	71,933	77,906	80,174
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	54,695	58,831	56,401
offseting disclosure, netting adjustment, derivative liability, fair value	(21)	0	0
offsetting disclosure, collateral value, derivative asset	54,716	58,831	56,401
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	0	0	0
offsetting disclosure, total gross amount not offset, derivative asset	0	0	0
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	17,247	19,080	23,786
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	17,247	19,080	23,786
offseting disclosure, netting adjustment, derivative asset, fair value	0	0	0
offsetting disclosure, collateral value, derivative liability	17,247	19,080	23,786
offsetting disclosure, total gross amount not offset, derivative liability	17,247	19,080	23,786
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	0	0	0
offseting disclosure, netting adjustment, derivative liability, fair value	0	0	0
offsetting disclosure, collateral value, derivative asset	0	0	0
Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	0	0	0
offsetting disclosure, total gross amount not offset, derivative asset	0	0	0
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	0	0	0
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	0	0	0
offseting disclosure, netting adjustment, derivative asset, fair value	0	0	0
offsetting disclosure, collateral value, derivative liability	0	0	0
offsetting disclosure, total gross amount not offset, derivative liability	0	0	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	0	0	0
offseting disclosure, netting adjustment, derivative liability, fair value	0	0	0
offsetting disclosure, collateral value, derivative asset	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	54,590	58,769	56,298
offsetting disclosure, total gross amount not offset, derivative asset	54,590	58,769	56,298
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	54,590	58,769	56,298
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	54,590	58,769	56,298
offseting disclosure, netting adjustment, derivative asset, fair value	(59)	(55)	(204)
offsetting disclosure, collateral value, derivative liability	54,649	58,824	56,502
offsetting disclosure, total gross amount not offset, derivative liability	54,590	58,769	56,298
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	54,590	58,769	56,298
offseting disclosure, netting adjustment, derivative liability, fair value	0	0	0
offsetting disclosure, collateral value, derivative asset	54,590	58,769	56,298
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Offsetting Disclosure for Derivative Contracts [Line Items]
offsetting disclosure, derivative asset, fair value, gross	105	62	103
offsetting disclosure, total gross amount not offset, derivative asset	105	62	103
offsetting disclosure, net amount total, derivative asset, fair value	0	0	0
offsetting disclosure, derivative liability, fair value, gross	96	57	90
offsetting disclosure, offset amount, derivative asset, fair value, gross	0	0	0
offsetting disclosure, net amount, derivative liability, falir value	96	57	90
offseting disclosure, netting adjustment, derivative asset, fair value	0	(14)	(24)
offsetting disclosure, collateral value, derivative liability	96	71	114
offsetting disclosure, total gross amount not offset, derivative liability	96	57	90
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	105	62	103
offseting disclosure, netting adjustment, derivative liability, fair value	(21)	0	0
offsetting disclosure, collateral value, derivative asset	$ 126	$ 62	$ 103