Reportable Operating Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Selected business segment financial information
Total interest income	$ 236,739	$ 244,934	$ 471,889	$ 489,886
Total interest expense	(73,156)	(92,083)	(147,780)	(182,608)
Net interest income (expense)	163,583	152,851	324,109	307,278
Provision for credit losses	(4,500)	(1,800)	(15,000)	(8,100)
Net interest income after provision for credit losses	159,083	151,051	309,109	299,178
Noninterest income	53,958	51,768	104,435	103,139
Salaries and employee benefits	59,501	57,737	119,605	116,999
Contracted services and professional fees	15,997	16,067	30,836	31,806
Occupancy	(7,934)	(7,377)	(16,034)	(14,318)
Equipment	(14,037)	(13,196)	(27,908)	(26,609)
Card rewards program	8,406	8,719	16,325	17,227
Noninterest expense	(124,939)	(122,086)	(248,499)	(250,899)
Income (loss) before (provision) benefit for income taxes	88,102	80,733	165,045	151,418
(Provision) benefit for income taxes	(14,855)	(18,812)	(32,550)	(35,277)
Net income	73,247	61,921	132,495	116,141
Operating Segments
Selected business segment financial information
Total interest income	236,739	244,934	471,889	489,886
Total interest expense	(73,156)	(92,083)	(147,780)	(182,608)
Net interest income (expense)	163,583	152,851	324,109	307,278
Provision for credit losses	(4,500)	(1,800)	(15,000)	(8,100)
Net interest income after provision for credit losses	159,083	151,051	309,109	299,178
Noninterest income	53,958	51,768	104,435	103,139
Salaries and employee benefits	(59,501)	(57,737)	(119,605)	(116,999)
Contracted services and professional fees	(15,997)	(16,067)	(30,836)	(31,806)
Occupancy	(7,934)	(7,377)	(16,034)	(14,318)
Equipment	(14,037)	(13,196)	(27,908)	(26,609)
Card rewards program	(8,406)	(8,719)	(16,325)	(17,227)
Other segment items	(19,064)	(18,990)	(37,791)	(43,940)
Noninterest expense	(124,939)	(122,086)	(248,499)	(250,899)
Income (loss) before (provision) benefit for income taxes	88,102	80,733	165,045	151,418
(Provision) benefit for income taxes	(14,855)	(18,812)	(32,550)	(35,277)
Net income	73,247	61,921	132,495	116,141
Other Segment Disclosures:
Depreciation and amortization	5,730	4,908	11,259	9,824
Segment earning assets	21,036,941	21,216,615	21,036,941	21,216,615
Retail Banking
Selected business segment financial information
Total interest income	20,655	19,167	42,057	41,193
Total interest expense	109,590	105,529	218,070	211,560
Net interest income (expense)	130,245	124,696	260,127	252,753
Noninterest income	27,754	26,296	54,405	52,331
Retail Banking | Operating Segments
Selected business segment financial information
Total interest income	84,660	83,500	169,072	167,723
Total interest expense	(53,112)	(60,700)	(107,993)	(119,072)
Net interest income (expense)	130,245	124,696	260,127	252,753
Provision for credit losses	(2,111)	(1,525)	(6,802)	(4,904)
Net interest income after provision for credit losses	128,134	123,171	253,325	247,849
Noninterest income	27,754	26,296	54,405	52,331
Salaries and employee benefits	(25,743)	(24,874)	(50,355)	(50,112)
Contracted services and professional fees	(2,919)	(3,038)	(5,972)	(5,919)
Occupancy	(7,414)	(7,375)	(14,709)	(14,791)
Equipment	(1,450)	(1,303)	(2,845)	(2,611)
Other segment items	(34,850)	(36,035)	(71,620)	(75,832)
Noninterest expense	(72,376)	(72,625)	(145,501)	(149,265)
Income (loss) before (provision) benefit for income taxes	83,512	76,842	162,229	150,915
(Provision) benefit for income taxes	(15,763)	(18,623)	(34,537)	(36,551)
Net income	67,749	58,219	127,692	114,364
Other Segment Disclosures:
Depreciation and amortization	992	1,124	2,041	2,259
Segment earning assets	7,335,543	7,438,823	7,335,543	7,438,823
Retail Banking | Intersegment Eliminations
Selected business segment financial information
Intersegment interest allocations	(64,005)	(64,333)	(127,015)	(126,530)
Intersegment interest allocations	162,702	166,229	326,063	330,632
Commercial Banking
Selected business segment financial information
Total interest income	28,081	32,431	58,221	65,967
Total interest expense	11,387	12,588	23,789	24,433
Net interest income (expense)	39,468	45,019	82,010	90,400
Noninterest income	19,039	18,623	36,794	36,581
Commercial Banking | Operating Segments
Selected business segment financial information
Total interest income	108,391	118,017	215,662	234,792
Total interest expense	(14,621)	(18,255)	(28,555)	(33,568)
Net interest income (expense)	39,468	45,019	82,010	90,400
Provision for credit losses	(2,389)	(1,675)	(7,698)	(5,388)
Net interest income after provision for credit losses	37,079	43,344	74,312	85,012
Noninterest income	19,039	18,623	36,794	36,581
Salaries and employee benefits	(4,964)	(4,780)	(9,755)	(9,776)
Contracted services and professional fees	(4,338)	(3,915)	(8,208)	(8,304)
Occupancy	(478)	(491)	(973)	(982)
Equipment	(472)	(233)	(921)	(594)
Card rewards program	(8,406)	(8,719)	(16,325)	(17,227)
Other segment items	(1,360)	(4,485)	(3,607)	(11,425)
Noninterest expense	(20,018)	(22,623)	(39,789)	(48,308)
Income (loss) before (provision) benefit for income taxes	36,100	39,344	71,317	73,285
(Provision) benefit for income taxes	(5,330)	(8,419)	(12,291)	(15,692)
Net income	30,770	30,925	59,026	57,593
Other Segment Disclosures:
Depreciation and amortization	68	67	136	135
Segment earning assets	7,025,480	6,925,612	7,025,480	6,925,612
Commercial Banking | Intersegment Eliminations
Selected business segment financial information
Intersegment interest allocations	(80,310)	(85,586)	(157,441)	(168,825)
Intersegment interest allocations	26,008	30,843	52,344	58,001
Treasury and Other
Selected business segment financial information
Total interest income	188,003	193,336	371,611	382,726
Total interest expense	(194,133)	(210,200)	(389,639)	(418,601)
Net interest income (expense)	(6,130)	(16,864)	(18,028)	(35,875)
Noninterest income	7,165	6,849	13,236	14,227
Treasury and Other | Operating Segments
Selected business segment financial information
Total interest income	43,688	43,417	87,155	87,371
Total interest expense	(5,423)	(13,128)	(11,232)	(29,968)
Net interest income (expense)	(6,130)	(16,864)	(18,028)	(35,875)
Provision for credit losses		1,400	(500)	2,192
Net interest income after provision for credit losses	(6,130)	(15,464)	(18,528)	(33,683)
Noninterest income	7,165	6,849	13,236	14,227
Salaries and employee benefits	(28,794)	(28,083)	(59,495)	(57,111)
Contracted services and professional fees	(8,740)	(9,114)	(16,656)	(17,583)
Occupancy	(42)	489	(352)	1,455
Equipment	(12,115)	(11,660)	(24,142)	(23,404)
Other segment items	17,146	21,530	37,436	43,317
Noninterest expense	(32,545)	(26,838)	(63,209)	(53,326)
Income (loss) before (provision) benefit for income taxes	(31,510)	(35,453)	(68,501)	(72,782)
(Provision) benefit for income taxes	6,238	8,230	14,278	16,966
Net income	(25,272)	(27,223)	(54,223)	(55,816)
Other Segment Disclosures:
Depreciation and amortization	4,670	3,717	9,082	7,430
Segment earning assets	6,675,918	6,852,180	6,675,918	6,852,180
Treasury and Other | Intersegment Eliminations
Selected business segment financial information
Intersegment interest allocations	144,315	149,919	284,456	295,355
Intersegment interest allocations	$ (188,710)	$ (197,072)	$ (378,407)	$ (388,633)