Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		$ 72,538	$ 72,725
Other revenue		18,665	17,655
Total noninterest income		91,202	90,380
Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		25,464	22,648
Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606	[1]	20,180	20,642
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		15,115	16,420
Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		9,295	9,472
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		2,484	3,544
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		3,448	5,195
Other revenue		7,998	7,488
Corporate and Commercial Specialty | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	0
Corporate and Commercial Specialty | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	0
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		3,388	4,225
Corporate and Commercial Specialty | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		328	315
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		(268)	655
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		68,899	67,198
Other revenue		5,325	6,838
Community, Consumer, and Business | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		25,461	22,624
Community, Consumer, and Business | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		20,180	20,401
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		11,708	12,183
Community, Consumer, and Business | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		8,919	9,154
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		2,632	2,837
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		191	332
Other revenue		5,342	3,329
Risk Management and Shared Services | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		3	24
Risk Management and Shared Services | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		0	241
Risk Management and Shared Services | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		19	12
Risk Management and Shared Services | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		49	3
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income In Scope of Topic 606		120	52
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income		11,445	12,683
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income		74,223	74,036
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income		$ 5,533	$ 3,661

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