Allowance for Loan and Lease Losses and Credit Quality Information - Rollforwards of the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan and lease losses
Balance, beginning of period		$ 171,041	$ 160,269	$ 156,054
Charge-offs		(84,728)	(79,092)	(64,085)
Recoveries		29,703	34,652	18,850
Net (charge-offs) recoveries		(55,025)	(44,440)	(45,235)
Provision for credit losses		46,768	68,443	65,874
Other	[1]	(5,338)	(13,231)	(16,424)
Balance, end of period		157,446	171,041	160,269
Consumer Real Estate
Allowance for loan and lease losses
Balance, beginning of period		47,168	59,448	67,992
Charge-offs		(7,129)	(11,861)	(18,624)
Recoveries		11,751	20,781	7,065
Net (charge-offs) recoveries		4,622	8,920	(11,559)
Provision for credit losses		(2,038)	(12,318)	9,304
Other	[1]	(4,886)	(8,882)	(6,289)
Balance, end of period		44,866	47,168	59,448
Commercial
Allowance for loan and lease losses
Balance, beginning of period		37,195	32,695	30,185
Charge-offs		(3,585)	(5,431)	(753)
Recoveries		228	833	373
Net (charge-offs) recoveries		(3,357)	(4,598)	(380)
Provision for credit losses		7,344	9,098	2,890
Other	[1]	0	0	0
Balance, end of period		41,182	37,195	32,695
Leasing and Equipment Finance
Allowance for loan and lease losses
Balance, beginning of period		22,528	21,350	19,018
Charge-offs		(9,695)	(10,816)	(7,738)
Recoveries		2,252	2,065	2,386
Net (charge-offs) recoveries		(7,443)	(8,751)	(5,352)
Provision for credit losses		8,960	10,067	7,706
Other	[1]	(254)	(138)	(22)
Balance, end of period		23,791	22,528	21,350
Inventory Finance
Allowance for loan and lease losses
Balance, beginning of period		13,233	13,932	11,128
Charge-offs		(6,928)	(3,014)	(2,623)
Recoveries		736	838	816
Net (charge-offs) recoveries		(6,192)	(2,176)	(1,807)
Provision for credit losses		5,613	1,367	4,540
Other	[1]	(198)	110	71
Balance, end of period		12,456	13,233	13,932
Auto Finance
Allowance for loan and lease losses
Balance, beginning of period		50,225	32,310	26,486
Charge-offs		(49,833)	(41,101)	(26,994)
Recoveries		11,289	6,625	3,853
Net (charge-offs) recoveries		(38,544)	(34,476)	(23,141)
Provision for credit losses		22,648	56,712	39,149
Other	[1]	0	(4,321)	(10,184)
Balance, end of period		34,329	50,225	32,310
Other
Allowance for loan and lease losses
Balance, beginning of period		692	534	1,245
Charge-offs		(7,558)	(6,869)	(7,353)
Recoveries		3,447	3,510	4,357
Net (charge-offs) recoveries		(4,111)	(3,359)	(2,996)
Provision for credit losses		4,241	3,517	2,285
Other	[1]	0	0	0
Balance, end of period		$ 822	$ 692	$ 534

[1] Primarily includes the transfer of the allowance for loan and lease losses to loans and leases held for sale.