Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 24,494	$ 23,926
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	11,920	5,275
Tax effect	(4,545)	(2,012)
Reclassification adjustment for gains (losses) included in net income	(122)
Tax effect	46
Net of tax amount	7,299	3,263
Unrealized gains (losses) on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding gains (losses) arising during period	(152)	(121)
Tax effect	58	46
Reclassification adjustment for losses included in interest expense	73	76
Tax effect	(28)	(29)
Net of tax amount	(49)	(28)
Change in pension and retiree medical plan obligation:
Reclassification adjustment for actuarial (gains) losses included in salaries and employee benefits	204	226
Tax effect	(78)	(86)
Net of tax amount	126	140
Other comprehensive income (loss), net of tax	7,376	3,375
Total comprehensive income	$ 31,870	$ 27,301