Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	$ 51,619	$ 53,522		$ 103,963	$ 105,284
Noninterest income (out-of-scope of Topic 606)(b)	23,840	19,921		45,962	63,502
Total noninterest income	75,458	73,443		149,925	168,786
Whitnell
Disaggregation of Revenue [Line Items]
Gain (Loss) on Sale and Maturity of Other Investments, Before Tax			$ 2,000		2,000
Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	21,332	22,706		43,735	45,120
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	16,506	15,549		33,363	30,404
Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	11,472	11,009		21,421	20,773
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	2,309	4,258		5,444	8,987
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	26,041	28,010		53,881	55,375
Noninterest income (out-of-scope of Topic 606)(b)	13,092	9,271		23,042	23,734
Corporate and Commercial Specialty | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	21,332	22,706		43,735	45,120
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	3,724	3,859		7,508	7,800
Corporate and Commercial Specialty | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	327	295		744	640
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	658	1,151		1,893	1,814
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	25,683	25,193		50,138	49,181
Noninterest income (out-of-scope of Topic 606)(b)	6,438	7,774		15,189	31,116
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	12,777	11,683		25,846	22,583
Community, Consumer, and Business | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	11,135	10,709		20,659	20,123
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	1,770	2,801		3,632	6,476
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	(105)	319		(56)	728
Noninterest income (out-of-scope of Topic 606)(b)	4,310	2,876		7,731	8,651
Risk Management and Shared Services | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	5	7		8	22
Risk Management and Shared Services | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	10	5		17	9
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest income (in-scope of Topic 606)	(120)	307		(81)	697
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income	39,133	37,281		76,923	79,109
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income	32,121	32,967		65,327	80,298
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income	$ 4,204	$ 3,195		$ 7,675	$ 9,379