Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	$ 66,933	$ 72,703	$ 138,282	$ 145,441
Noninterest Income (out-of-scope of Topic 606)	187,557	23,134	214,515	41,599
Total noninterest income	254,490	95,837	352,796	187,040
Gain (Loss) on Disposition of Assets for Financial Service Operations	157,361	871	157,284	1,438
Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	22,430	22,985	45,038	48,449
Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	20,916	20,691	41,732	40,870
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	11,484	15,426	26,706	30,542
Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	8,922	10,177	18,529	19,472
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	3,181	3,424	6,277	6,108
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	20,690	20,047	41,426	39,387
Noninterest Income (out-of-scope of Topic 606)	10,002	11,220	23,698	19,026
Corporate and Commercial Specialty | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	47	49	123	174
Corporate and Commercial Specialty | Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	15,814	15,369	31,621	30,469
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	4,307	3,309	7,859	6,806
Corporate and Commercial Specialty | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	228	455	743	889
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	294	865	1,081	1,049
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	46,163	52,381	96,698	105,479
Noninterest Income (out-of-scope of Topic 606)	12,394	9,742	19,509	14,919
Community, Consumer, and Business | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	22,381	22,933	44,910	48,268
Community, Consumer, and Business | Wealth management fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	5,102	5,321	10,111	10,402
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	7,173	12,104	18,838	23,703
Community, Consumer, and Business | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	8,647	9,674	17,693	18,486
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	2,861	2,349	5,147	4,621
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	80	275	158	574
Noninterest Income (out-of-scope of Topic 606)	165,161	2,172	171,307	7,653
Risk Management and Shared Services | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	3	3	6	7
Risk Management and Shared Services | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	4	14	10	32
Risk Management and Shared Services | Card-based fees(b)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	47	48	94	97
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	26	210	49	438
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income	30,691	31,267	65,124	58,414
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income	58,557	62,123	116,207	120,398
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income	$ 165,242	$ 2,447	$ 171,465	$ 8,228