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Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands | Mar. 31, 2024 | Dec. 31, 2023
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity Securities, FV-NI | $ 1 | $ 1
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 2,286,682 | 2,346,864
Other Borrowings, Fair Value Disclosure | 123,824 | 123,116
Securities available-for-sale, at fair value | 2,286,682 | 2,346,864
Credit-Link Notes |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other Borrowings, Fair Value Disclosure | 123,824 | 123,116
Agency residential CMOs |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 281,569 | 284,334
Collateralized loan obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 109,078 | 108,416
Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 33,259 | 28,083
Agency commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 243,387 | 253,306
SBA securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 12,911 | 13,739
Corporate Debt Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 277,198 | 267,232
U.S. Treasury securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) |  | 4,968
Private label commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 19,491 | 20,813
Private Label Collateralized Mortgage Obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 153,412 | 158,412
Asset-backed Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 18,908 | 19,952
Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity warrants |  | 3,689
Fair Value, Measurements, Recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity warrants | 3,708 | 3,689
Interest rate and economic contracts | 10,205 | 8,309
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 2,286,682 |
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 1,137,469 | 1,187,609
Fair Value, Measurements, Recurring | Agency residential CMOs |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 281,569 | 284,334
Fair Value, Measurements, Recurring | Collateralized loan obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 109,078 | 108,416
Fair Value, Measurements, Recurring | Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 33,259 | 28,083
Fair Value, Measurements, Recurring | Agency commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 243,387 | 253,306
Fair Value, Measurements, Recurring | SBA securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 12,911 | 13,739
Fair Value, Measurements, Recurring | Corporate Debt Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 277,198 | 267,232
Fair Value, Measurements, Recurring | U.S. Treasury securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) |  | 4,968
Fair Value, Measurements, Recurring | Private label commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 19,491 | 20,813
Fair Value, Measurements, Recurring | Private Label Collateralized Mortgage Obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 153,412 | 158,412
Fair Value, Measurements, Recurring | Asset-backed Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 18,908 | 19,952
Fair Value, Measurements, Recurring | Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity warrants | 0 | 0
Interest rate and economic contracts | 0 | 0
Equity Securities, FV-NI | 1 | 1
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 4,968
Other Borrowings | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Government agency and government-sponsored enterprise pass through securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Agency residential CMOs |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Collateralized loan obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Agency commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | SBA securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Corporate Debt Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) |  | 4,968
Fair Value, Measurements, Recurring | Level 1 | Private label commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Private Label Collateralized Mortgage Obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 1 | Asset-backed Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity warrants | 0 | 0
Interest rate and economic contracts | 10,205 | 8,309
Equity Securities, FV-NI | 0 | 0
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 2,284,582 | 2,301,647
Other Borrowings | 0 | 0
Fair Value, Measurements, Recurring | Level 2 | Government agency and government-sponsored enterprise pass through securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 1,137,469 | 1,187,609
Fair Value, Measurements, Recurring | Level 2 | Agency residential CMOs |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 281,569 | 284,334
Fair Value, Measurements, Recurring | Level 2 | Collateralized loan obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 109,078 | 108,416
Fair Value, Measurements, Recurring | Level 2 | Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 33,259 | 28,083
Fair Value, Measurements, Recurring | Level 2 | Agency commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 243,387 | 253,306
Fair Value, Measurements, Recurring | Level 2 | SBA securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 12,911 | 13,739
Fair Value, Measurements, Recurring | Level 2 | Corporate Debt Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 275,098 | 226,983
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) |  | 0
Fair Value, Measurements, Recurring | Level 2 | Private label commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 19,491 | 20,813
Fair Value, Measurements, Recurring | Level 2 | Private Label Collateralized Mortgage Obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 153,412 | 158,412
Fair Value, Measurements, Recurring | Level 2 | Asset-backed Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 18,908 | 19,952
Fair Value, Measurements, Recurring | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Equity warrants | 3,708 | 3,689
Interest rate and economic contracts | 0 | 0
Equity Securities, FV-NI | 0 | 0
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 2,100 | 40,249
Other Borrowings | 123,824 | 123,116
Fair Value, Measurements, Recurring | Level 3 | Government agency and government-sponsored enterprise pass through securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Agency residential CMOs |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Collateralized loan obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Municipal securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Agency commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | SBA securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Corporate Debt Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 2,100 | 40,249
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) |  | 0
Fair Value, Measurements, Recurring | Level 3 | Private label commercial MBS |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Private Label Collateralized Mortgage Obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | 0 | 0
Fair Value, Measurements, Recurring | Level 3 | Asset-backed Securities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Securities available-for-sale, at fair value, net of allowance for credit losses (amortized cost of $2,657,281 and $2,699,255, respectively) | $ 0 | $ 0

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