Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net change in Unrealized (losses) gains, tax (benefit) expense	$ 779	$ 6,479
Reclassification adjustment for gains, tax expense	114	116
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	59	65
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	(12)	306
Net change in cash flow hedge, tax expense	$ (69)	$ 0