Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	$ 72,713	$ 72,718	$ 216,373	$ 218,270
Noninterest Income (out-of-scope of Topic 606)	28,137	15,583	71,517	53,252
Total noninterest income	100,850	88,300	287,890	271,522
Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	20,954	21,636	69,403	68,279
Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,015	21,224	61,885	62,198
Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	16,561	16,904	47,102	49,714
Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	10,501	9,826	29,973	29,454
Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	3,683	3,128	8,010	8,624
Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	4,326	4,109	10,291	12,625
Noninterest Income (out-of-scope of Topic 606)	9,125	8,171	28,924	26,531
Corporate and Commercial Specialty | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	3,182	3,669	9,765	11,680
Corporate and Commercial Specialty | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	336	353	1,001	1,014
Corporate and Commercial Specialty | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	809	88	(475)	(69)
Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	68,346	68,518	205,666	205,065
Noninterest Income (out-of-scope of Topic 606)	12,787	5,320	28,026	19,059
Community, Consumer, and Business | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,041	21,677	69,483	68,289
Community, Consumer, and Business | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	21,015	21,224	61,885	61,932
Community, Consumer, and Business | Service charges and deposit account fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	13,367	13,210	37,293	37,984
Community, Consumer, and Business | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	10,120	9,489	28,829	28,449
Community, Consumer, and Business | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	2,803	2,918	8,175	8,411
Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	41	91	417	580
Noninterest Income (out-of-scope of Topic 606)	6,224	2,092	14,567	7,662
Risk Management and Shared Services | Insurance commissions and fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	(87)	(41)	(80)	(9)
Risk Management and Shared Services | Wealth management fees
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	0	0	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)	12	25	44	50
Risk Management and Shared Services | Card-based fees(a)
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	45	(15)	143	(9)
Risk Management and Shared Services | Other revenue
Disaggregation of Revenue [Line Items]
Noninterest Income (in-scope of Topic 606)	71	122	310	282
Operating Segments [Member] | Corporate and Commercial Specialty
Disaggregation of Revenue [Line Items]
Total noninterest income	13,452	12,280	39,215	39,156
Operating Segments [Member] | Community, Consumer, and Business
Disaggregation of Revenue [Line Items]
Total noninterest income	81,133	73,838	233,692	224,124
Operating Segments [Member] | Risk Management and Shared Services
Disaggregation of Revenue [Line Items]
Total noninterest income	$ 6,265	$ 2,183	$ 14,983	$ 8,242