Tax Credit Investments Tax Credit Investments - Affordable Housing Tax Credit Investments and Other Tax Credit Investments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Schedule of Equity Method Investments [Line Items]
Affordable housing tax credits and other tax benefits	$ 1,731	$ 1,393
Other tax credit investment credits and tax benefits	3,618	3,188
Total reduction in income tax expense	5,349	4,581
Non-Interest Expenses [Member]
Schedule of Equity Method Investments [Line Items]
Affordable housing tax credit investment losses	677	440
Affordable housing tax credit investment impairment losses	488	0
Other tax credit investment losses	(297)	(398)
Other tax credit investment impairment losses	(3,034)	(2,878)
Total amortization of tax credit investments recorded in non-interest expense	$ 4,496	$ 3,716