Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		$ 71,122	$ 72,825	$ 143,660	$ 145,553
Other revenue		24,715	20,017	43,380	37,670
Total noninterest income		95,837	92,842	187,040	183,222
Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		22,985	23,996	48,449	46,644
Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[1]	20,691	20,333	40,870	40,975
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		15,426	16,390	30,542	32,810
Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[2]	10,177	10,155	19,472	19,628
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		1,843	1,952	4,327	5,496
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		2,517	3,320	5,964	8,515
Other revenue		11,801	10,874	19,799	18,361
Corporate and Commercial Specialty | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	0	0	0
Corporate and Commercial Specialty | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	0	0	0
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		3,195	3,786	6,583	8,011
Corporate and Commercial Specialty | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[2]	338	347	666	661
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		(1,016)	(813)	(1,284)	(157)
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		68,421	69,349	137,320	136,547
Other revenue		9,914	6,901	15,239	13,739
Community, Consumer, and Business | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		22,982	23,988	48,442	46,612
Community, Consumer, and Business | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		20,691	20,307	40,870	40,708
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		12,218	12,590	23,926	24,773
Community, Consumer, and Business | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[2]	9,791	9,806	18,709	18,960
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		2,740	2,657	5,372	5,493
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		184	156	375	490
Other revenue		3,000	2,242	8,343	5,570
Risk Management and Shared Services | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		3	7	7	32
Risk Management and Shared Services | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	26	0	267
Risk Management and Shared Services | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		14	13	32	25
Risk Management and Shared Services | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[2]	48	3	97	6
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		119	108	239	160
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income		14,318	14,194	25,763	26,876
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income		78,335	76,250	152,559	150,286
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income		$ 3,185	$ 2,399	$ 8,718	$ 6,059

[1] Includes trust, asset management, brokerage, and annuity fees.

[2] (a) Certain card-based fees are out-of-scope of Topic 606.