CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net change in Unrealized (losses) gains, tax (benefit) expense	$ 14,538	$ 5,452
Reclassification adjustment for gains, tax expense	166	4
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	21	29
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	1	(8)
Reclassification adjustment related to derivatives, tax benefit (expense)	$ 501	$ 199