Revenues Revenue Recognition by Segment (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			$ 212,278	$ 246,077	$ 288,247
Noninterest Income, Outside of Scope of Topic 606			120,086	267,979	92,577
Total noninterest income			332,364	514,056	380,824
Whitnell
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Gain (Loss) on Sale and Maturity of Other Investments, Before Tax		$ 2,000
Wealth management fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606	[1]		89,854	84,957	83,467
Service charges and deposit account fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			64,406	56,307	63,135
Card-based fees(a)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			43,124	38,605	39,912
Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			336	45,245	89,104
Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			14,558	20,963	12,629
Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			113,866	105,678	97,899
Noninterest Income, Outside of Scope of Topic 606			56,471	43,778	38,198
Corporate and Commercial Specialty [Member] | Wealth management fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			89,854	83,570	80,719
Corporate and Commercial Specialty [Member] | Service charges and deposit account fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			18,635	16,903	13,342
Corporate and Commercial Specialty [Member] | Card-based fees(a)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			1,790	1,534	1,827
Corporate and Commercial Specialty [Member] | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			138	208	364
Corporate and Commercial Specialty [Member] | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			3,450	3,462	1,647
Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			96,592	141,775	188,666
Noninterest Income, Outside of Scope of Topic 606			49,865	43,962	35,046
Community, Consumer and Business [Member] | Wealth management fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			0	1,387	2,838
Community, Consumer and Business [Member] | Service charges and deposit account fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			45,739	39,371	49,744
Community, Consumer and Business [Member] | Card-based fees(a)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			41,313	36,937	37,895
Community, Consumer and Business [Member] | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			190	45,027	88,727
Community, Consumer and Business [Member] | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			9,349	19,053	9,462
Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			1,820	(1,375)	1,532
Noninterest Income, Outside of Scope of Topic 606			13,750	180,237	19,483
Risk Management and Shared Services [Member] | Wealth management fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			0	0	(90)
Risk Management and Shared Services [Member] | Service charges and deposit account fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			32	33	49
Risk Management and Shared Services [Member] | Card-based fees(a)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			21	134	190
Risk Management and Shared Services [Member] | Insurance commissions and fees
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			8	10	13
Risk Management and Shared Services [Member] | Other revenue
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Noninterest Income In Scope of Topic 606			1,760	(1,552)	1,370
Risk Management and Shared Serivies [Member] | ABRC [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Gain (Loss) on Disposition of Assets for Financial Service Operations				163,000
Operating Segments [Member] | Corporate and Commercial Specialty [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income			170,338	149,456	136,097
Operating Segments [Member] | Community, Consumer and Business [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income			146,457	185,737	223,712
Operating Segments [Member] | Risk Management and Shared Services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total noninterest income			$ 15,570	$ 178,862	$ 21,015

[1] (a)