Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	$ 49,243	$ 72,414	$ 187,521	$ 217,853
Noninterest Income (out-of-scope of Topic 606)	26,302	28,436	240,821	70,037
Total noninterest income	75,545	100,850	428,342	287,890
Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	114	20,954	45,153	69,403
Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,152	21,015	62,884	61,885
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	14,283	16,561	40,989	47,102
Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	10,207	10,501	28,735	29,973
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	3,487	3,383	9,763	9,490
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	27,541	24,870	77,688	73,308
Noninterest Income (out-of-scope of Topic 606)	9,864	8,801	33,566	27,827
Corporate and Commercial Specialty | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	57	109	179	283
Corporate and Commercial Specialty | Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,152	20,313	61,496	59,828
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	4,458	3,307	12,316	10,113
Corporate and Commercial Specialty | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	474	451	1,216	1,341
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	1,400	690	2,481	1,743
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,738	47,322	109,712	143,750
Noninterest Income (out-of-scope of Topic 606)	11,220	12,612	30,730	27,533
Community, Consumer, and Business | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	55	20,842	44,965	69,110
Community, Consumer, and Business | Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	0	792	1,387	2,148
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	9,816	13,243	28,653	36,945
Community, Consumer, and Business | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	9,699	10,004	27,392	28,490
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	2,168	2,441	7,315	7,057
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	(36)	222	121	797
Noninterest Income (out-of-scope of Topic 606)	5,218	7,023	176,525	14,675
Risk Management and Shared Services | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	2	3	8	10
Risk Management and Shared Services | Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	0	(90)	0	(90)
Risk Management and Shared Services | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	10	12	19	44
Risk Management and Shared Services | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	34	45	127	143
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	(82)	252	(33)	690
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income	37,405	33,671	111,254	101,135
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income	32,958	59,934	140,442	171,283
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income	5,182	7,245	176,646	15,472
Operating Segments [Member] | Risk Management and Shared Serivies [Member]
Disaggregation of Revenue [Line Items]
Total noninterest income	$ 5,182	$ 7,245	$ 176,646	$ 15,472