Fair Value of Assets and Liabilities (Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Financial Assets:
Securities sold under agreements to repurchase with original maturities exceeding three months	$ 0	$ 700,000,000
Interest-bearing deposits with banks	1,988,719,000	5,372,603,000
Available-for-sale securities	3,243,017,000	2,327,793,000
Held-to-maturity securities	2,949,821,000	2,900,694,000
Equity securities with readily determinable fair value	110,365,000	90,511,000
FHLB and FRB stock, at cost	224,759,000	135,378,000
Brokerage customer receivables	16,387,000	26,068,000
Mortgage loans held-for-sale, at fair value	299,935,000	817,912,000
Accrued interest receivable and other assets	1,391,342,000	1,084,115,000
Financial Liabilities:
Federal Home Loan Bank advances	2,316,071,000	1,241,071,000
Other borrowings	596,614,000	494,136,000
Subordinated notes	437,392,000	436,938,000
Junior subordinated debentures	253,566,000	253,566,000
Carrying Value
Financial Assets:
Cash and cash equivalents	490,966,000	411,205,000
Securities sold under agreements to repurchase with original maturities exceeding three months	0	700,000,000
Interest-bearing deposits with banks	1,988,719,000	5,372,603,000
Available-for-sale securities	3,243,017,000	2,327,793,000
Held-to-maturity securities	3,640,567,000	2,942,285,000
Trading account securities	1,127,000	1,061,000
Equity securities with readily determinable fair value	110,365,000	90,511,000
FHLB and FRB stock, at cost	224,759,000	135,378,000
Brokerage customer receivables	16,387,000	26,068,000
Mortgage loans held-for-sale, at fair value	299,935,000	817,912,000
Nonqualified deferred compensation assets	13,899,000	16,240,000
Derivative assets	296,848,000	165,008,000
Accrued interest receivable and other assets	379,719,000	268,921,000
Total financial assets	49,902,793,000	48,064,089,000
Financial Liabilities:
Non-maturity deposits	38,167,409,000	38,126,796,000
Deposits with stated maturities	4,735,135,000	3,968,789,000
Federal Home Loan Bank advances	2,316,071,000	1,241,071,000
Other borrowings	596,614,000	494,136,000
Subordinated notes	437,392,000	436,938,000
Junior subordinated debentures	253,566,000	253,566,000
Derivative liabilities	338,078,000	123,000,000
Accrued interest payable	22,176,000	9,304,000
Total financial liabilities	46,866,441,000	44,653,600,000
Carrying Value | Loans held-for-investment, at fair value
Financial Assets:
Loans held-for-investment	179,932,000	38,598,000
Carrying Value | Loans held-for-investment, at amortized cost
Financial Assets:
Loans held-for-investment	39,016,553,000	34,750,506,000
Fair Value
Financial Assets:
Cash and cash equivalents	490,966,000	411,205,000
Securities sold under agreements to repurchase with original maturities exceeding three months	0	700,000,000
Interest-bearing deposits with banks	1,988,719,000	5,372,603,000
Available-for-sale securities	3,243,017,000	2,327,793,000
Trading account securities	1,127,000	1,061,000
Equity securities with readily determinable fair value	110,365,000	90,511,000
FHLB and FRB stock, at cost	224,759,000	135,378,000
Brokerage customer receivables	16,387,000	26,068,000
Mortgage loans held-for-sale, at fair value	299,935,000	817,912,000
Nonqualified deferred compensation assets	13,899,000	16,240,000
Derivative assets	296,848,000	165,008,000
Accrued interest receivable and other assets	379,719,000	268,921,000
Total financial assets	48,214,172,000	48,569,870,000
Financial Liabilities:
Non-maturity deposits	38,167,409,000	38,126,796,000
Deposits with stated maturities	4,085,058,000	3,965,372,000
Federal Home Loan Bank advances	2,219,983,000	1,186,280,000
Other borrowings	569,342,000	494,670,000
Subordinated notes	409,395,000	472,684,000
Junior subordinated debentures	253,405,000	212,226,000
Derivative liabilities	338,078,000	123,000,000
Accrued interest payable	22,176,000	9,304,000
Total financial liabilities	46,064,846,000	44,590,332,000
Fair Value | Loans held-for-investment, at fair value
Financial Assets:
Loans held-for-investment	179,932,000	38,598,000
Fair Value | Loans held-for-investment, at amortized cost
Financial Assets:
Loans held-for-investment	$ 38,018,678,000	$ 35,297,878,000