Fair Values of Assets and Liabilities - Schedule of Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Financial Assets:
Interest-bearing deposits with banks	$ 4,238,237	$ 4,409,753	$ 2,131,077
Available-for-sale securities	4,220,305	4,141,482	4,387,598
Held-to-maturity securities	2,922,813	2,910,550	3,111,954
Equity securities with readily determinable fair value	270,442	215,412	119,777
FHLB and FRB stock, at cost	281,893	281,407	224,657
Brokerage customer receivables	0	18,102	13,382
Mortgage loans held-for-sale, at fair value	316,804	331,261	339,884
Accrued interest receivable and other	1,598,255	1,739,334	1,580,142
Financial Liabilities:
FHLB advances	3,151,309	3,151,309	2,676,751
Other borrowings	529,269	534,803	575,408
Subordinated notes	298,360	298,283	437,965
Junior subordinated debentures	253,566	253,566	253,566
Carrying Value
Financial Assets:
Cash and cash equivalents	616,279	458,536	379,886
Interest-bearing deposits with banks	4,238,237	4,409,753	2,131,077
Available-for-sale securities	4,220,305	4,141,482	4,387,598
Held-to-maturity securities	3,564,490	3,613,263	3,810,015
Trading account securities	0	4,072	2,184
Equity securities with readily determinable fair value	270,442	215,412	119,777
FHLB and FRB stock, at cost	281,893	281,407	224,657
Brokerage customer receivables	0	18,102	13,382
Mortgage loans held-for-sale, at fair value	316,804	331,261	339,884
Nonqualified deferred compensation assets	16,396	16,653	15,953
Derivative assets	204,257	200,027	259,264
Accrued interest receivable and other	573,254	563,625	487,933
Total	63,010,747	62,308,630	55,402,316
Financial Liabilities:
Non-maturity deposits	43,601,801	43,092,318	38,554,438
Deposits with stated maturities	9,968,237	9,420,031	7,894,420
FHLB advances	3,151,309	3,151,309	2,676,751
Other borrowings	529,269	534,803	575,408
Subordinated notes	298,360	298,283	437,965
Junior subordinated debentures	253,566	253,566	253,566
Derivative liabilities	181,198	241,750	324,364
Accrued interest payable	60,127	48,364	64,943
Total financial liabilities	58,043,867	57,040,424	50,781,855
Carrying Value | Loans held-for-investment, at fair value
Financial Assets:
Loans held-for-investment	126,521	158,795	144,371
Carrying Value | Loans held-for-investment, at amortized cost
Financial Assets:
Loans held-for-investment	48,581,869	47,896,242	43,086,335
Fair Value
Financial Assets:
Cash and cash equivalents	616,279	458,536	379,886
Interest-bearing deposits with banks	4,238,237	4,409,753	2,131,077
Available-for-sale securities	4,220,305	4,141,482	4,387,598
Held-to-maturity securities	2,922,813	2,910,550	3,111,954
Trading account securities	0	4,072	2,184
Equity securities with readily determinable fair value	270,442	215,412	119,777
FHLB and FRB stock, at cost	281,893	281,407	224,657
Brokerage customer receivables	0	18,102	13,382
Mortgage loans held-for-sale, at fair value	316,804	331,261	339,884
Nonqualified deferred compensation assets	16,396	16,653	15,953
Derivative assets	204,257	200,027	259,264
Accrued interest receivable and other	573,254	563,625	487,933
Total	61,531,858	60,779,924	53,686,539
Financial Liabilities:
Non-maturity deposits	43,601,801	43,092,318	38,554,438
Deposits with stated maturities	9,964,441	9,423,976	7,872,870
FHLB advances	3,164,174	3,153,524	2,669,780
Other borrowings	529,297	534,406	573,752
Subordinated notes	294,495	286,683	413,003
Junior subordinated debentures	253,571	253,588	253,574
Derivative liabilities	181,198	241,750	324,364
Accrued interest payable	60,127	48,364	64,943
Total financial liabilities	58,049,104	57,034,609	50,726,724
Fair Value | Loans held-for-investment, at fair value
Financial Assets:
Loans held-for-investment	126,521	158,795	144,371
Fair Value | Loans held-for-investment, at amortized cost
Financial Assets:
Loans held-for-investment	$ 47,744,657	$ 47,070,249	$ 42,068,619