Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 134,743	$ 50,244	$ 64,080
Net change in unrealized gains (losses) on investment securities available for sale
Net unrealized gains (losses) arising during the period, net of tax expense (benefit) of ($2,223), $1,813, and ($2,968), respectively	(6,695)	3,073	(4,838)
Less: reclassification adjustment for net gains on sales realized in net income, net of tax expense of $5, $704, and $900, respectively	(16)	(1,280)	(1,469)
Net change in unrealized gains (losses) on investment securities available for sale	(6,711)	1,793	(6,307)
Net change in securities held to maturity
Net change in securities held to maturity	(444)	(394)	(403)
Net change in securities held to maturity	(444)	(394)	(403)
Amortization of unrealized gain on securities reclassified to held-to-maturity, net of tax expense of $136, $241, and $248, respectively
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, net of tax (benefit) expense of ($56), $103, and ($37), respectively	(31)	(90)	169
Net change in unfunded pension liability	(31)	(90)	169
Net change in cash flow hedge
Net unrealized (loss) arising during the period, net of tax (benefit) of ($29), ($113), and ($1,086), respectively	(56)	(184)	(1,772)
Net change in cash flow hedge	(56)	(184)	(1,772)
Total other comprehensive (loss) income	(7,242)	1,125	(8,313)
Total comprehensive income	$ 127,501	$ 51,369	$ 55,767