Components of Other Comprehensive Income/(Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Debt securities gains/(losses), net	$ 0	$ 1	$ 52	$ 450
Provision/(benefit) for income taxes	83,925	13,596	133,553	57,903
Interest and fees on loans	331,000	205,220	954,467	578,264
All other expense	25,701	28,113	112,032	72,554
Net income/(loss)	274,716	71,769	455,702	225,361
Reclassifications from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income/(loss)	2,906	761	6,521	1,304
Reclassifications from AOCI | Securities AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Debt securities gains/(losses), net	0	(1)	(52)	(450)
Provision/(benefit) for income taxes	0	0	13	172
Net income/(loss)	0	(1)	(39)	(278)
Reclassifications from AOCI | Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision/(benefit) for income taxes	(253)	398	(354)	1,487
Interest and fees on loans	1,024	(1,041)	1,433	(3,886)
Net income/(loss)	771	(643)	1,079	(2,399)
Reclassifications from AOCI | Pension and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Provision/(benefit) for income taxes	(701)	(872)	(1,799)	(2,469)
All other expense	2,836	2,277	7,280	6,450
Net income/(loss)	$ 2,135	$ 1,405	$ 5,481	$ 3,981