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		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 49,355,319		$ 49,355,319		$ 50,210,295
Gross loan charge-offs
Total	48,221	$ 8,918	111,460	$ 52,818
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,407,443		1,407,443		1,579,982
Year two, fiscal year before current fiscal year	1,021,166		1,021,166		1,123,368
Year three, two years before current fiscal year	852,271		852,271		784,426
Year four, three years before current fiscal year	548,365		548,365		379,097
Year five, four years before current fiscal year	279,838		279,838		217,248
More than five years before current fiscal year	601,040		601,040		588,062
Revolving Loans Amortized Cost Basis	5,051,609		5,051,609		4,524,198
Revolving Loans Converted to Term Loans	37,555		37,555		34,162
Total	9,799,287		9,799,287		9,230,543
Gross loan charge-offs
Total	7,501	7,487	36,515	37,399
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,348,640		1,348,640		1,494,417
Year two, fiscal year before current fiscal year	929,724		929,724		1,047,513
Year three, two years before current fiscal year	778,008		778,008		765,335
Year four, three years before current fiscal year	529,959		529,959		377,047
Year five, four years before current fiscal year	271,271		271,271		211,504
More than five years before current fiscal year	541,718		541,718		523,430
Revolving Loans Amortized Cost Basis	4,776,972		4,776,972		4,382,361
Revolving Loans Converted to Term Loans	10,865		10,865		29,798
Total	9,187,157		9,187,157		8,831,405
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	17,974		17,974		70,807
Year two, fiscal year before current fiscal year	5,769		5,769		73,423
Year three, two years before current fiscal year	61,307		61,307		15,296
Year four, three years before current fiscal year	2,131		2,131		358
Year five, four years before current fiscal year	5,081		5,081		1,870
More than five years before current fiscal year	15,369		15,369		915
Revolving Loans Amortized Cost Basis	111,758		111,758		99,981
Revolving Loans Converted to Term Loans	4,025		4,025		139
Total	223,414		223,414		262,789
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	14,938		14,938		3,100
Year two, fiscal year before current fiscal year	80,428		80,428		1,837
Year three, two years before current fiscal year	12,945		12,945		2,629
Year four, three years before current fiscal year	15,347		15,347		1,714
Year five, four years before current fiscal year	3,486		3,486		1,221
More than five years before current fiscal year	16,767		16,767		5,900
Revolving Loans Amortized Cost Basis	158,661		158,661		29,569
Revolving Loans Converted to Term Loans	22,665		22,665		4,225
Total	325,237		325,237		50,195
Commercial and industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	25,891		25,891		11,658
Year two, fiscal year before current fiscal year	5,245		5,245		595
Year three, two years before current fiscal year	11		11		1,166
Year four, three years before current fiscal year	928		928
Year four, three years before current fiscal year					(22)
Year five, four years before current fiscal year	0		0		2,653
More than five years before current fiscal year	27,186		27,186		57,817
Revolving Loans Amortized Cost Basis	4,218		4,218		12,287
Revolving Loans Converted to Term Loans	0		0		0
Total	63,479		63,479		86,154
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	30,402,196		30,402,196		31,970,047
Gross loan charge-offs
Total	38,123	$ 255	69,277	$ 12,226
Commercial real estate | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,535,962		1,535,962		4,272,246
Year two, fiscal year before current fiscal year	3,686,033		3,686,033		6,738,948
Year three, two years before current fiscal year	6,133,636		6,133,636		5,052,212
Year four, three years before current fiscal year	4,590,042		4,590,042		3,022,501
Year five, four years before current fiscal year	2,712,451		2,712,451		2,469,773
More than five years before current fiscal year	7,328,728		7,328,728		5,957,963
Revolving Loans Amortized Cost Basis	820,047		820,047		622,497
Revolving Loans Converted to Term Loans	107,833		107,833		107,099
Total	26,914,732		26,914,732		28,243,239
Commercial real estate | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,387,811		1,387,811		4,088,835
Year two, fiscal year before current fiscal year	3,122,589		3,122,589		6,630,322
Year three, two years before current fiscal year	5,507,668		5,507,668		4,791,190
Year four, three years before current fiscal year	4,108,362		4,108,362		2,789,275
Year five, four years before current fiscal year	2,408,835		2,408,835		2,329,385
More than five years before current fiscal year	6,536,122		6,536,122		5,385,809
Revolving Loans Amortized Cost Basis	661,967		661,967		618,056
Revolving Loans Converted to Term Loans	107,833		107,833		104,839
Total	23,841,187		23,841,187		26,737,711
Commercial real estate | Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	83,281		83,281		125,296
Year two, fiscal year before current fiscal year	418,398		418,398		82,917
Year three, two years before current fiscal year	306,716		306,716		248,900
Year four, three years before current fiscal year	222,191		222,191		184,720
Year five, four years before current fiscal year	85,499		85,499		69,949
More than five years before current fiscal year	295,662		295,662		358,059
Revolving Loans Amortized Cost Basis	116,488		116,488		26
Revolving Loans Converted to Term Loans	0		0		183
Total	1,528,235		1,528,235		1,070,050
Commercial real estate | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	64,870		64,870		58,115
Year two, fiscal year before current fiscal year	141,986		141,986		25,709
Year three, two years before current fiscal year	319,252		319,252		12,122
Year four, three years before current fiscal year	259,489		259,489		48,506
Year five, four years before current fiscal year	208,213		208,213		70,439
More than five years before current fiscal year	496,874		496,874		214,095
Revolving Loans Amortized Cost Basis	41,592		41,592		4,415
Revolving Loans Converted to Term Loans					2,077
Total	1,532,276		1,532,276		435,478
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	3,060		3,060
Year three, two years before current fiscal year	0		0
Year four, three years before current fiscal year	0		0
Year five, four years before current fiscal year	9,904		9,904
More than five years before current fiscal year	70		70
Revolving Loans Amortized Cost Basis	0		0
Revolving Loans Converted to Term Loans	0		0
Total	13,034		13,034
Commercial real estate | Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	488,344		488,344		760,480
Year two, fiscal year before current fiscal year	764,741		764,741		675,097
Year three, two years before current fiscal year	531,958		531,958		276,612
Year four, three years before current fiscal year	150,973		150,973		10,318
Year five, four years before current fiscal year	29,597		29,597		40,584
More than five years before current fiscal year	40,011		40,011		61,228
Revolving Loans Amortized Cost Basis	1,423,073		1,423,073		1,762,890
Revolving Loans Converted to Term Loans	58,767		58,767		139,599
Total	3,487,464		3,487,464		3,726,808
Commercial real estate | Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	477,695		477,695		753,759
Year two, fiscal year before current fiscal year	764,741		764,741		655,198
Year three, two years before current fiscal year	501,433		501,433		267,336
Year four, three years before current fiscal year	140,941		140,941		10,318
Year five, four years before current fiscal year	22,325		22,325		40,584
More than five years before current fiscal year	40,011		40,011		43,560
Revolving Loans Amortized Cost Basis	1,339,753		1,339,753		1,762,890
Revolving Loans Converted to Term Loans	58,767		58,767		139,599
Total	3,345,666		3,345,666		3,673,244
Commercial real estate | Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	1,591		1,591
Year two, fiscal year before current fiscal year	0		0
Year three, two years before current fiscal year	10,685		10,685
Year four, three years before current fiscal year	5,090		5,090
Year five, four years before current fiscal year	0		0
More than five years before current fiscal year	0		0
Revolving Loans Amortized Cost Basis	41,245		41,245
Revolving Loans Converted to Term Loans	0		0
Total	58,611		58,611
Commercial real estate | Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	9,058		9,058		6,721
Year two, fiscal year before current fiscal year	0		0		0
Year three, two years before current fiscal year	9,016		9,016		9,276
Year four, three years before current fiscal year	4,942		4,942		0
Year five, four years before current fiscal year	0		0		0
More than five years before current fiscal year	0		0		17,668
Revolving Loans Amortized Cost Basis	42,075		42,075		0
Revolving Loans Converted to Term Loans	0		0		0
Total	65,091		65,091		33,665
Commercial real estate | Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, current fiscal year	0		0		0
Year two, fiscal year before current fiscal year	0		0		19,899
Year three, two years before current fiscal year	10,824		10,824		0
Year four, three years before current fiscal year	0		0		0
Year five, four years before current fiscal year	7,272		7,272		0
More than five years before current fiscal year	0		0		0
Revolving Loans Amortized Cost Basis	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	$ 18,096		18,096		19,899
Commercial and Industrial and Commercial Real Estate
Gross loan charge-offs
Year one, gross loan charge-offs			191		307
Year two, gross loan charge-offs			15,144		12,919
Year three, gross loan charge-offs			6,841		28,438
Year four, gross loan charge-offs			25,943		6,946
Year five, gross loan charge-offs			30,669		5,031
More than five years gross loan charge-offs			21,417		13,446
Revolving Loans Amortized Cost Basis			3,930		3,729
Revolving Loans Converted to Term Loans			1,657		145
Total			$ 105,792		$ 70,961