Accumulated Other Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net			$ 314	$ 16,674
Loan interest income	$ 125,462	$ 121,851	249,456	244,273
Total before tax	69,576	44,777	133,977	62,635
Income tax provision	(14,537)	(8,195)	(27,085)	(11,425)
Net Income	55,039	36,582	106,892	51,210
Compensation and employee benefits	53,450	46,043	105,186	100,885
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	314	0	314	249
Total before tax	764	0	764	249
Income tax provision	(178)	0	(178)	(58)
Net Income	586	0	586	191
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of unrealized gains and losses related to available for sale securities transfer
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Loan interest income	450	0	450	0
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	(149)	(103)	(299)	(207)
Income tax provision	34	24	69	48
Net Income	(115)	(79)	(230)	(159)
Compensation and employee benefits	(149)	(103)	(299)	(207)
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	2,602	2,190	5,178	3,130
Income tax provision	(604)	(510)	(1,203)	(728)
Net Income	1,998	1,680	3,975	2,402
Loans	$ 2,602	$ 2,190	$ 5,178	$ 3,130