Segment Reporting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Income Statement Data Abstract
Net interest income	$ 725,855	$ 762,957	$ 835,674
Net intersegment interest income (expense)	0	0	0
Segment net interest income	725,855	762,957	835,674
Noninterest income	332,364	514,056	380,824
Total revenue	1,058,219	1,277,012	1,216,498
Provision for credit losses	(88,011)	174,006	16,000
Noninterest expense	709,924	776,034	793,988
Income before income taxes	436,307	326,972	406,509
Income tax expense	85,313	20,200	79,720
Net income	350,994	306,771	326,790
Segment Balance Sheet Data
Allocated goodwill	1,104,992	1,109,300	1,176,230
Operating Segments | Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
Net interest income	373,856	395,135	447,979
Net intersegment interest income (expense)	26,710	10,400	(52,200)
Segment net interest income	400,565	405,535	395,779
Noninterest income	170,338	149,456	136,097
Total revenue	570,903	554,991	531,876
Provision for credit losses	62,795	59,780	49,341
Noninterest expense	229,444	209,507	233,655
Income before income taxes	278,664	285,705	248,879
Income tax expense	49,772	53,193	47,480
Net income	228,891	232,512	201,399
Segment Balance Sheet Data
Allocated goodwill	525,836	530,144	530,144
Operating Segments | Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
Net interest income	276,854	295,297	301,563
Net intersegment interest income (expense)	53,668	54,203	93,331
Segment net interest income	330,522	349,500	394,894
Noninterest income	146,457	185,737	223,712
Total revenue	476,978	535,237	618,606
Provision for credit losses	18,138	21,862	18,594
Noninterest expense	387,033	429,565	467,086
Income before income taxes	71,808	83,810	132,925
Income tax expense	15,080	17,600	27,914
Net income	56,728	66,210	105,011
Segment Balance Sheet Data
Allocated goodwill	579,156	579,156	646,086
Operating Segments | Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
Net interest income	75,146	72,525	86,132
Net intersegment interest income (expense)	(80,378)	(64,603)	(41,130)
Segment net interest income	(5,232)	7,922	45,001
Noninterest income	15,570	178,862	21,015
Total revenue	10,338	186,784	66,017
Provision for credit losses	(168,944)	92,365	(51,935)
Noninterest expense	93,446	136,962	93,247
Income before income taxes	85,836	(42,543)	24,705
Income tax expense	20,461	(50,593)	4,325
Net income	65,374	8,050	20,379
Segment Balance Sheet Data
Allocated goodwill	$ 0	$ 0	$ 0