Business Segments - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Average interest earning assets	$ 37,386,219	$ 34,674,075
Interest income	331,798	363,793
Interest expense	39,131	98,454
Net interest income (loss)	292,667	265,339
(Credit) provision for credit losses	8,656	34,683
Net interest income (loss) after provision for credit losses	284,011	230,656
Non-interest income	31,233	41,397
Non-interest expense	160,213	155,656
Internal transfer expense (income)	0	0
Income Before Income Taxes	$ 155,031	$ 116,397
Return on average interest earning assets (pre-tax)	1.66%	1.34%
Consumer Lending | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 7,049,252	$ 7,217,144
Interest income	60,845	68,255
Interest expense	6,415	19,700
Net interest income (loss)	54,430	48,555
(Credit) provision for credit losses	(2,635)	6,785
Net interest income (loss) after provision for credit losses	57,065	41,770
Non-interest income	13,685	14,677
Non-interest expense	19,849	19,871
Internal transfer expense (income)	19,502	20,335
Income Before Income Taxes	$ 31,399	$ 16,241
Return on average interest earning assets (pre-tax)	1.78%	0.90%
Commercial Lending | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 25,533,227	$ 22,782,284
Interest income	252,336	264,875
Interest expense	23,235	62,186
Net interest income (loss)	229,101	202,689
(Credit) provision for credit losses	11,676	27,139
Net interest income (loss) after provision for credit losses	217,425	175,550
Non-interest income	7,713	15,599
Non-interest expense	25,531	24,158
Internal transfer expense (income)	70,555	64,196
Income Before Income Taxes	$ 129,052	$ 102,795
Return on average interest earning assets (pre-tax)	2.02%	1.80%
Investment Management | Operating Segments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 4,803,740	$ 4,674,647
Interest income	19,509	31,769
Interest expense	4,371	12,760
Net interest income (loss)	15,138	19,009
(Credit) provision for credit losses	(385)	759
Net interest income (loss) after provision for credit losses	15,523	18,250
Non-interest income	2,331	3,142
Non-interest expense	1,777	387
Internal transfer expense (income)	13,277	13,175
Income Before Income Taxes	$ 2,800	$ 7,830
Return on average interest earning assets (pre-tax)	0.23%	0.67%
Corporate and Other Adjustments | Corporate and Other Adjustments
Segment Reporting Information [Line Items]
Average interest earning assets	$ 0	$ 0
Interest income	(892)	(1,106)
Interest expense	5,110	3,808
Net interest income (loss)	(6,002)	(4,914)
(Credit) provision for credit losses	0	0
Net interest income (loss) after provision for credit losses	(6,002)	(4,914)
Non-interest income	7,504	7,979
Non-interest expense	113,056	111,240
Internal transfer expense (income)	(103,334)	(97,706)
Income Before Income Taxes	$ (8,220)	$ (10,469)