Revenues Revenue Recognition by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	$ 290,084	$ 262,175	$ 252,651
Noninterest Income, Outside of Scope of Topic 606	65,483	70,505	100,232
Total noninterest income	355,568	332,680	352,883
Insurance Commissions and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	89,511	81,474	80,795
Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	66,075	64,427	66,609
Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	41,325	35,881	34,527
Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	54,316	50,191	46,867
Brokerage Commission and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	28,246	19,935	16,235
Other Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	10,611	10,267	7,617
Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	17,009	17,941	15,022
Noninterest Income, Outside of Scope of Topic 606	35,311	34,355	32,754
Corporate and Commercial Specialty [Member] | Insurance Commissions and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0
Corporate and Commercial Specialty [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	14,981	16,006	15,378
Corporate and Commercial Specialty [Member] | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	1,343	1,163	740
Corporate and Commercial Specialty [Member] | Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0
Corporate and Commercial Specialty [Member] | Brokerage Commission and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	0	0	0
Corporate and Commercial Specialty [Member] | Other Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	685	772	(1,096)
Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	272,363	243,883	237,265
Noninterest Income, Outside of Scope of Topic 606	23,284	22,367	40,677
Community, Consumer and Business [Member] | Insurance Commissions and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	89,472	81,468	80,795
Community, Consumer and Business [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	51,025	48,344	51,047
Community, Consumer and Business [Member] | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	39,883	34,695	33,765
Community, Consumer and Business [Member] | Fiduciary and Trust [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	54,316	50,191	46,866
Community, Consumer and Business [Member] | Brokerage Commission and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	28,024	19,935	16,235
Community, Consumer and Business [Member] | Other Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	9,643	9,249	8,556
Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	712	351	364
Noninterest Income, Outside of Scope of Topic 606	6,889	13,783	26,801
Risk Management and Shared Services [Member] | Insurance Commissions and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	39	6	0
Risk Management and Shared Services [Member] | Deposit Account [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	69	77	184
Risk Management and Shared Services [Member] | Card-Based and No Loan Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	98	23	22
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	0	0
Risk Management and Shared Services [Member] | Brokerage Commission and Fees [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	222	0	0
Risk Management and Shared Services [Member] | Other Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	283	245	158
Operating Segments [Member] | Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income	52,321	52,297	47,776
Operating Segments [Member] | Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income	295,647	266,250	277,942
Operating Segments [Member] | Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income	$ 7,600	$ 14,133	$ 27,165