Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 12,234	$ 12,725	$ 25,123	$ 29,636
Net change in unrealized (losses) gains on investment securities available-for-sale
Net unrealized (losses) gains arising during the period, net of tax expense (benefit) of ($3,692), $5,932, ($893) and $11,537, respectively	(6,024)	9,678	(1,457)	18,824
Less: reclassification adjustment for net gains on sales realized in net income, net of tax expense of $181, $139, $352 and $358, respectively	(296)	(226)	(576)	(585)
Net change in unrealized (losses) gains on investment securities available-for-sale	(6,320)	9,452	(2,033)	18,239
Net change in securities held-to-maturity
Amortization of unrealized gain on securities reclassified to held-to-maturity, net of tax benefit of ($120), $ 0, ($120), $ 0, respectively	(37)		(208)
Net change in unfunded pension liability
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, net of tax (benefit) expense of ($9), $36, ($18) and $36, respectively	(15)	60	(30)	60
Total other comprehensive income (loss)	(6,372)	9,512	(2,271)	18,299
Total comprehensive income	$ 5,862	$ 22,237	$ 22,852	$ 47,935