CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income		$ 52,084	$ 46,367	$ 43,805
Change in securities available for sale:
Unrealized holding gain (loss) on securities available for sale arising during the period		(7,238)	(2,720)	10,739
Reclassification adjustment for (gains)/losses included in net income		(66)	(42)	224
Net securities gain (loss) activity during the period		(7,304)	(2,762)	10,963
Tax effect		2,746	1,131	(4,358)
Net of tax amount		(4,558)	(1,631)	6,605
Defined benefit pension plans:
Net loss on defined benefit pension plans		(151)	(325)	(654)
Amortization of net actuarial loss	[1]	215	244	197
Net gain (loss) activity during the period		64	(81)	(457)
Tax effect		(35)	24	176
Net of tax amount		29	(57)	(281)
Total other comprehensive income (loss), net of tax		(4,529)	(1,688)	6,324
Comprehensive income		$ 47,555	$ 44,679	$ 50,129

[1] Included in the computation of net pension plan expense as more fully discussed in Note 11.