CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net change in Unrealized (losses) gains, tax (benefit) expense	$ (1,846)	$ 761	$ (6,958)	$ 3,498
Reclassification adjustment for gains, tax expense	0	261	5	628
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	36	60	109	181
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	(9)	(15)	1	(42)
Reclassification adjustment related to derivatives, tax benefit (expense)	$ (75)	$ 26	$ (391)	$ 118