Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net change in Unrealized (losses) gains, tax (benefit) expense	$ 761	$ (682)	$ 3,498	$ 8,668
Reclassification adjustment for gains, tax expense	261	395	628	718
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	60	60	181	187
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	(15)	(14)	(42)	266
Net change in cash flow hedge, tax expense	$ 26	$ 38	$ 118	$ 38