Schedule of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Change in net unrealized Gain during period:
Change in net unrealized gain during period, before tax amount	$ 8,613	$ 10,608
Change in net unrealized gain during period, tax expense (benefit)	3,360	4,174
Change in net unrealized gain during period, net of tax amount	5,253	6,434
Reclassification adjustment for gains included in net income:
Reclassification adjustment for gains included in net income, before tax amount	21	(6)
Reclassification adjustment for gains included in net income, tax expense (benefit)	8	(2)
Reclassification adjustment for gains included in net income, net of tax amount	13	(4)
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	465	451
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Tax	183	177
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	282	274
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	(2,197)	0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(835)	0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(1,362)	0
Change in net actuarial loss:
Change in net actuarial loss, before tax amount	15	15
Change in net actuarial loss, tax expense (benefit)	6	6
Change in net actuarial loss, net of tax amount	9	9
Other comprehensive income (loss):
Other comprehensive income (loss), before tax	6,917	11,068
Total other comprehensive income, tax expense (benefit)	2,722	4,355
Total other comprehensive income, net of tax amount	$ 4,195	$ 6,713