Loans and Allowance for Credit Losses for Loans - Internal Loan Classification Risk by Loan Portfolio Class by Origination Year (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 48,657,128		$ 48,799,711
Gross loan charge-offs
Total	44,019	$ 24,900
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	416,709		1,824,953
Year two, fiscal year before current fiscal year	1,720,855		854,030
Year three, two years before current fiscal year	802,792		772,815
Year four, three years before current fiscal year	723,701		492,961
Year five, four years before current fiscal year	421,284		250,075
More than five years before current fiscal year	711,377		524,794
Revolving Loans Amortized Cost Basis	5,321,319		5,155,993
Revolving Loans Converted to Term Loans	32,168		55,779
Total	10,150,205		9,931,400
Gross loan charge-offs
Total	28,456	14,293
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	402,895		1,769,585
Year two, fiscal year before current fiscal year	1,683,588		828,087
Year three, two years before current fiscal year	775,801		703,962
Year four, three years before current fiscal year	657,761		476,091
Year five, four years before current fiscal year	405,335		246,992
More than five years before current fiscal year	592,244		392,834
Revolving Loans Amortized Cost Basis	4,880,356		4,804,095
Revolving Loans Converted to Term Loans	8,136		6,006
Total	9,406,116		9,227,652
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	13,814		30,755
Year two, fiscal year before current fiscal year	1,186		3,553
Year three, two years before current fiscal year	5,973		59,434
Year four, three years before current fiscal year	3,413		11,646
Year five, four years before current fiscal year	11,255		270
More than five years before current fiscal year	14,628		72,514
Revolving Loans Amortized Cost Basis	210,855		147,254
Revolving Loans Converted to Term Loans	3,766		10,762
Total	264,890		336,188
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		24,613
Year two, fiscal year before current fiscal year	36,081		13,479
Year three, two years before current fiscal year	13,898		9,415
Year four, three years before current fiscal year	62,525		4,296
Year five, four years before current fiscal year	4,373		2,813
More than five years before current fiscal year	52,761		7,382
Revolving Loans Amortized Cost Basis	217,195		201,053
Revolving Loans Converted to Term Loans	20,266		39,011
Total	407,099		302,062
Commercial and industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0
Year two, fiscal year before current fiscal year	0		8,911
Year three, two years before current fiscal year	7,120		4
Year four, three years before current fiscal year	2		928
Year five, four years before current fiscal year	321		0
More than five years before current fiscal year	51,744		52,064
Revolving Loans Amortized Cost Basis	12,913		3,591
Revolving Loans Converted to Term Loans	0		0
Total	72,100		65,498
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	29,114,556		29,644,958
Gross loan charge-offs
Total	13,423	$ 8,798
Commercial real estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	638,695		2,338,118
Year two, fiscal year before current fiscal year	2,267,477		3,433,126
Year three, two years before current fiscal year	3,093,123		5,988,114
Year four, three years before current fiscal year	5,798,174		4,400,609
Year five, four years before current fiscal year	4,250,687		2,604,959
More than five years before current fiscal year	9,265,733		6,937,081
Revolving Loans Amortized Cost Basis	695,277		749,597
Revolving Loans Converted to Term Loans	78,455		78,621
Total	26,087,621		26,530,225
Commercial real estate | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	600,990		2,097,314
Year two, fiscal year before current fiscal year	2,070,782		2,941,270
Year three, two years before current fiscal year	2,622,556		5,310,807
Year four, three years before current fiscal year	5,052,632		3,883,333
Year five, four years before current fiscal year	3,667,440		2,302,480
More than five years before current fiscal year	8,058,437		6,086,608
Revolving Loans Amortized Cost Basis	514,996		597,266
Revolving Loans Converted to Term Loans	78,387		78,621
Total	22,666,220		23,297,699
Commercial real estate | Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		156,394
Year two, fiscal year before current fiscal year	127,965		380,852
Year three, two years before current fiscal year	308,325		289,669
Year four, three years before current fiscal year	293,431		192,614
Year five, four years before current fiscal year	218,617		55,739
More than five years before current fiscal year	359,533		327,732
Revolving Loans Amortized Cost Basis	165,641		141,164
Revolving Loans Converted to Term Loans	0		0
Total	1,473,512		1,544,164
Commercial real estate | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	37,705		84,410
Year two, fiscal year before current fiscal year	68,730		107,944
Year three, two years before current fiscal year	159,182		387,638
Year four, three years before current fiscal year	452,111		288,906
Year five, four years before current fiscal year	330,105		236,927
More than five years before current fiscal year	834,911		520,858
Revolving Loans Amortized Cost Basis	14,640		11,167
Revolving Loans Converted to Term Loans	68		0
Total	1,897,452		1,637,850
Commercial real estate | Commercial real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0
Year two, fiscal year before current fiscal year	0		3,060
Year three, two years before current fiscal year	3,060		0
Year four, three years before current fiscal year	0		35,756
Year five, four years before current fiscal year	34,525		9,813
More than five years before current fiscal year	12,852		1,883
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term Loans	0		0
Total	50,437		50,512
Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	153,394		568,710
Year two, fiscal year before current fiscal year	563,135		680,260
Year three, two years before current fiscal year	619,201		346,587
Year four, three years before current fiscal year	333,597		102,776
Year five, four years before current fiscal year	83,090		25,228
More than five years before current fiscal year	72,943		47,665
Revolving Loans Amortized Cost Basis	1,143,795		1,284,863
Revolving Loans Converted to Term Loans	57,780		58,644
Total	3,026,935		3,114,733
Commercial real estate | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	153,394		545,597
Year two, fiscal year before current fiscal year	549,099		680,260
Year three, two years before current fiscal year	614,599		334,899
Year four, three years before current fiscal year	324,001		92,765
Year five, four years before current fiscal year	69,166		17,955
More than five years before current fiscal year	72,943		45,161
Revolving Loans Amortized Cost Basis	1,062,079		1,224,698
Revolving Loans Converted to Term Loans	24,850		58,644
Total	2,870,131		2,999,979
Commercial real estate | Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		13,278
Year two, fiscal year before current fiscal year	13,263		0
Year three, two years before current fiscal year	4,527		664
Year four, three years before current fiscal year	646		5,069
Year five, four years before current fiscal year	9,447		0
More than five years before current fiscal year	0		2,504
Revolving Loans Amortized Cost Basis	29,494		16,691
Revolving Loans Converted to Term Loans	0		0
Total	57,377		38,206
Commercial real estate | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		9,835
Year two, fiscal year before current fiscal year	773		0
Year three, two years before current fiscal year	75		8,950
Year four, three years before current fiscal year	8,950		4,942
Year five, four years before current fiscal year	4,477		0
More than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	52,222		43,474
Revolving Loans Converted to Term Loans	32,930		0
Total	99,427		67,201
Commercial real estate | Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year			0
Year two, fiscal year before current fiscal year			0
Year three, two years before current fiscal year			2,074
Year four, three years before current fiscal year			0
Year five, four years before current fiscal year			7,273
More than five years before current fiscal year			0
Revolving Loans Amortized Cost Basis			0
Revolving Loans Converted to Term Loans			0
Total			9,347
Commercial and Industrial and Commercial Real Estate
Gross loan charge-offs
Year one, gross loan charge-offs	0		706
Year two, gross loan charge-offs	70		31,809
Year three, gross loan charge-offs	842		7,523
Year four, gross loan charge-offs	2,488		44,610
Year five, gross loan charge-offs	7,308		66,632
More than five years gross loan charge-offs	6,807		49,436
Revolving Loans Amortized Cost Basis	9,776		3,930
Revolving Loans Converted to Term Loans	14,588		2,148
Total	$ 41,879		$ 206,794