Revenues Revenue Recognition by Segment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		$ 288,247	$ 290,084	$ 262,175
Noninterest Income, Outside of Scope of Topic 606		92,577	65,484	70,505
Total noninterest income		380,824	355,568	332,680
Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		89,104	89,511	81,474
Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	[1]	83,467	82,562	70,126
Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		63,135	66,075	64,427
Card-based fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		39,912	39,810	34,997
Other fee-based revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		12,629	12,126	11,151
Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		15,258	17,009	17,941
Noninterest Income, Outside of Scope of Topic 606		38,024	35,311	34,355
Corporate and Commercial Specialty [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		12,883	14,981	16,006
Corporate and Commercial Specialty [Member] | Card-based fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		1,373	1,334	1,125
Corporate and Commercial Specialty [Member] | Other fee-based revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		1,002	694	811
Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		272,062	272,363	243,883
Noninterest Income, Outside of Scope of Topic 606		35,687	23,284	22,367
Community, Consumer and Business [Member] | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		89,091	89,472	81,468
Community, Consumer and Business [Member] | Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		83,467	82,341	70,126
Community, Consumer and Business [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		50,203	51,025	48,344
Community, Consumer and Business [Member] | Card-based fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		38,349	38,439	33,849
Community, Consumer and Business [Member] | Other fee-based revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		10,952	11,087	10,095
Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		926	712	351
Noninterest Income, Outside of Scope of Topic 606		18,866	6,889	13,783
Risk Management and Shared Services [Member] | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		13	39	6
Risk Management and Shared Services [Member] | Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		0	222	0
Risk Management and Shared Services [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		49	69	77
Risk Management and Shared Services [Member] | Card-based fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		190	37	23
Risk Management and Shared Services [Member] | Other fee-based revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606		675	345	245
Operating Segments [Member] | Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income		53,282	52,321	52,297
Operating Segments [Member] | Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income		307,750	295,647	266,250
Operating Segments [Member] | Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income		$ 19,793	$ 7,600	$ 14,133

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