Accumulated Other Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net	$ 249	$ 1,847
Total before tax	17,858	56,656
Income tax provision	(3,230)	(10,785)
Compensation and employee benefits	54,842	52,085
Net income	14,628	45,871
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Available-for-Sale Debt Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net	249	(1,847)
Total before tax	249	(1,847)
Income tax provision	(58)	430
Net income	191	(1,417)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Pension Plan Liability [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(104)	(80)
Income tax provision	24	19
Compensation and employee benefits	(104)	(80)
Net income	(80)	(61)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized gains and losses from hedging instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	940	0
Income tax provision	(218)	0
Net income	722	0
Interest income	$ 940	$ 0