Income Taxes Income Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Taxes at statutory rate									$ 11,660	$ 12,178	$ 36,285
Tax-exempt interest									(1,265)	(1,452)	(1,162)
State income tax expense (benefit) net of federal tax benefit									221	148	333
Valuation allowance									0	0	(14,423)
Income Tax Credits and Adjustments									(717)	(293)	0
Low income housing tax credit partnerships									617	0	0
Change in state tax rate									248	0	0
Other, net									292	404	513
Total income tax expense (benefit)	$ 4,077	$ 1,988	$ 4,464	$ 527	$ (553)	$ 308	$ 5,791	$ 5,439	$ 11,056	$ 10,985	$ 21,546