CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 28,740	$ 20,570	$ 66,090	$ 39,507
Net change in unrealized (loss) gains on investment securities available for sale
Net unrealized (loss) gains arising during the period, net of tax (benefit) expense of ($1,398), $1,958, ($5,112) and $2,737, respectively	(4,501)	3,241	(16,328)	4,513
Less: reclassification adjustment for net gains on sales realized in net income, net of tax expense of $0, $253, $5, and $367, respectively	0	(455)	(16)	(661)
Net change in unrealized gains (losses) on investment securities available-for-sale	(4,501)	2,786	(16,344)	3,852
Net change in securities held to maturity
Amortization of unrealized gain on securities reclassified to held-to-maturity, net of tax benefit of $36, $62, $73 and $121, respectively	(117)	(97)	(236)	(198)
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), ($15), $9, and ($27), respectively	(30)	(22)	29	(45)
Net change in cash flow hedge
Net unrealized (loss) gain arising during the period, net of tax (benefit) tax of ($76), $161, ($316) and $92 respectively	(245)	262	(1,010)	150
Total other comprehensive (loss) income	(4,893)	2,929	(17,561)	3,759
Total comprehensive income	$ 23,847	$ 23,499	$ 48,529	$ 43,266