Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (765)	$ 14,369
Available-for-sale investment securities:
Gross unrealized holding gain arising during the period	22,268	8,725
Related tax expense	(4,676)	(1,832)
Less: reclassification adjustment for net gain included in net income	319	30
Related tax expense	(67)	(6)
Net effect on other comprehensive income	17,340	6,869
Defined benefit plans:
Net (loss) gain arising during the period	(365)	2
Related tax (benefit) expense	(76)	0
Amortization of unrecognized loss and service cost on benefit plans	28	17
Related tax expense	(6)	(4)
Recognition of loss due to settlement and curtailment	368	0
Related tax expense	77	0
Net effect on other comprehensive income	24	15
Cash flow hedges:
Net loss arising during the period	(9,730)	(1,833)
Related tax benefit	2,043	385
Net effect on other comprehensive loss	(7,687)	(1,448)
Total other comprehensive income, net of tax	9,677	5,436
Total comprehensive income	$ 8,912	$ 19,805