Fair Value Measurements - Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	4,708,519	4,843,487
Other Borrowings, Fair Value Disclosure	123,065	132,030
Securities available-for-sale, at fair value	4,708,519	4,843,487
Credit-Link Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Borrowings, Fair Value Disclosure	123,065	132,030
Agency residential CMOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	439,227	457,063
Collateralized loan obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	104,823	102,261
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	342,789	339,326
Agency commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	479,957	487,606
SBA securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	15,082	17,250
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	280,513	311,905
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	673,083	670,070
Private label commercial MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	23,200	26,827
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	159,507	166,724
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	21,725	22,413
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity warrants		4,048
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity warrants	3,883	4,048
Interest rate and economic contracts	7,759	7,814
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	4,708,519
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	2,168,613	2,242,042
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	439,227	457,063
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	104,823	102,261
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	342,789	339,326
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	479,957	487,606
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	15,082	17,250
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	280,513	311,905
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	673,083	670,070
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	23,200	26,827
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	159,507	166,724
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	21,725	22,413
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	673,083	670,070
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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, respectively)	673,083	670,070
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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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	7,759	7,814
Equity Securities, FV-NI	0	0
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	4,028,446	4,173,417
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	2,168,613	2,242,042
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	439,227	457,063
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	104,823	102,261
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	342,789	339,326
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	479,957	487,606
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	15,082	17,250
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	273,523	311,905
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	0	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 (amortized cost of $5,515,823 and $5,654,617, respectively)	23,200	26,827
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	159,507	166,724
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	21,725	22,413
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity warrants	3,883	4,048
Interest rate and economic contracts	0	0
Equity Securities, FV-NI	0	0
Securities available-for-sale, at fair value (amortized cost of $5,515,823 and $5,654,617, respectively)	6,990	0
Other Borrowings	123,065	132,030
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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, respectively)	6,990	0
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 (amortized cost of $5,515,823 and $5,654,617, respectively)	0	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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, 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 (amortized cost of $5,515,823 and $5,654,617, respectively)	$ 0	$ 0