Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 24,516	$ 24,872	$ 49,010	$ 48,798
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	4,631	(8,226)	16,551	(2,953)
Tax effect	(1,766)	3,100	(6,311)	1,090
Reclassification adjustment for gains (losses) included in net income			(122)
Tax effect			46
Net of tax amount	2,865	(5,126)	10,164	(1,863)
Unrealized gains (losses) on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding gains (losses) arising during period	(46)	29	(198)	(92)
Tax effect	18	(11)	75	35
Reclassification adjustment for losses included in interest expense	68	64	142	140
Tax effect	(26)	(24)	(54)	(53)
Net of tax amount	14	58	(35)	30
Change in pension and retiree medical plan obligation:
Reclassification adjustment for actuarial (gains) losses included in salaries and employee benefits	204	225	408	450
Tax effect	(78)	(86)	(156)	(171)
Net of tax amount	126	139	252	279
Other comprehensive income (loss), net of tax	3,005	(4,929)	10,381	(1,554)
Total comprehensive income	$ 27,521	$ 19,943	$ 59,391	$ 47,244