Fair Value Measurements (Details 2) - USD ($) $ in Thousands		Jun. 30, 2026	Dec. 31, 2025
ASSETS
Held to Maturity, Fair Value, Total		$ 1,117,644	$ 1,190,733
Federal Home Loan Bank Stock		13,631	21,835
Bank Owned Life Insurance		381,230	378,576
LIABILITIES
Federal Home Loan Bank and other borrowings (f)		216,719	416,549
Long-Term Line of Credit		124,984	49,953
Subordinated Debt		296,898	296,483
Reported Value Measurement
ASSETS
Loans Receivable, Fair Value Disclosure	[1]	18,127,775	18,234,032
Estimate of Fair Value Measurement
ASSETS
Loans Receivable, Fair Value Disclosure	[1]	17,770,945	17,842,036
Deposits [Member]
LIABILITIES
Time certificates of deposits (f)	[2]	17,142,663	16,858,570
Accrued Liabilities, Fair Value Disclosure	[2]	17,142,663	16,858,570
Time certificates of deposits (f)
LIABILITIES
Time certificates of deposits (f)	[3]	3,249,455	3,268,220
Accrued Liabilities, Fair Value Disclosure	[3]	3,241,759	3,262,605
Federal Home Loan Bank and other borrowings (f)
LIABILITIES
Federal Home Loan Bank and other borrowings (f)	[3]	216,719	416,549
Federal Home Loan Bank Borrowings, Fair Value Disclosure	[3]	217,510	417,352
Junior subordinated debentures (g)
LIABILITIES
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	[4]	62,864	62,862
Accrued Liabilities, Fair Value Disclosure	[4]	62,689	62,492
Subordinated debentures (h)
LIABILITIES
Subordinated Debt	[3]	296,898	296,483
Accrued Liabilities, Fair Value Disclosure	[3]	309,000	308,794
Line of Credit
LIABILITIES
Lines of Credit, Fair Value Disclosure	[3]	128,366	52,494
Long-Term Line of Credit	[3]	124,984	49,953
Significant Other Observable Inputs (Level 2) | Deposits [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	[2]	17,142,663	16,858,570
Significant Other Observable Inputs (Level 2) | Time certificates of deposits (f)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	[3]	3,241,759	3,262,605
Significant Other Observable Inputs (Level 2) | Federal Home Loan Bank and other borrowings (f)
LIABILITIES
Federal Home Loan Bank Borrowings, Fair Value Disclosure	[3]	217,510	417,352
Significant Other Observable Inputs (Level 2) | Junior subordinated debentures (g)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	[4]	62,689	62,492
Significant Other Observable Inputs (Level 2) | Line of Credit
LIABILITIES
Lines of Credit, Fair Value Disclosure	[3]	128,366	52,494
Significant Unobservable Inputs (Level 3) | Estimate of Fair Value Measurement
ASSETS
Loans Receivable, Fair Value Disclosure	[1]	17,770,945	17,842,036
Significant Unobservable Inputs (Level 3) | Subordinated debentures (h)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	[3]	309,000	308,794
U.S. treasury securities
ASSETS
Debt Securities, Held-to-maturity	[5]	100,911	100,872
Held to Maturity, Fair Value, Total	[5]	97,503	97,124
U.S. treasury securities | Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	[5]	97,503	97,124
Agency mortgage-backed securities
ASSETS
Debt Securities, Held-to-maturity	[5]	653,630	694,903
Held to Maturity, Fair Value, Total	[5]	615,058	659,415
Agency mortgage-backed securities | Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	[5]	615,058	659,415
Agency collateralized mortgage obligations
ASSETS
Debt Securities, Held-to-maturity	[5]	348,671	370,698
Held to Maturity, Fair Value, Total	[5]	303,073	325,798
Agency collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	[5]	303,073	325,798
Small Business Administration Pooled Securities [Member]
ASSETS
Debt Securities, Held-to-maturity	[5]	107,098	112,554
Held to Maturity, Fair Value, Total	[5]	102,010	108,396
Small Business Administration Pooled Securities [Member] | Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	[5]	102,010	108,396
Investment in Federal Home Loan Bank Stock [Member]
ASSETS
Federal Home Loan Bank Stock	[6]	13,631	21,835
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	[6]	13,631	21,835
Investment in Federal Home Loan Bank Stock [Member] | Significant Other Observable Inputs (Level 2)
ASSETS
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	[6]	13,631	21,835
Investment in Federal Home Loan Bank Stock [Member] | Significant Unobservable Inputs (Level 3)
ASSETS
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	[6]	0
Cash Surrender Value [Member]
ASSETS
Cash Surrender Value, Fair Value Disclosure	[7]	381,230	378,576
Bank Owned Life Insurance	[7]	381,230	378,576
Cash Surrender Value [Member] | Significant Other Observable Inputs (Level 2)
ASSETS
Cash Surrender Value, Fair Value Disclosure	[7]	$ 381,230	$ 378,576

[1] Fair value of loans is measured using the exit price valuation method, determined primarily by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities or cash flows, while incorporating liquidity and credit assumptions. Additionally, this amount excludes individually assessed collateral dependent loans, which are deemed to be marked to fair value on a non-recurring basis.

[2] Fair value of demand deposits, savings and interest checking accounts and money market deposits is the amount payable on demand at the reporting date.

[3] Fair value was determined by discounting anticipated future cash payments using rates currently available for instruments with similar remaining maturities.

[4] Fair value was determined based upon market prices of securities with similar terms and maturities.

[5] The fair values presented are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on quoted market prices of comparable instruments and/or discounted cash flow analysis.

[6] Federal Home Loan Bank stock has no quoted market value and is carried at cost, therefore the carrying amount approximates fair value.

[7] Cash surrender value of life insurance policies is recorded at its cash surrender value (or the amount that can be realized upon surrender of the policy), therefore, carrying amount approximates fair value.