Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	$ 3,757,663	$ 3,797,187
Securities available-for-sale, at fair value	3,757,663	3,797,187
Equity Securities, FV-NI	2,471	2,998
Derivative Liability	1,152	755
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity warrants		3,434
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	1,125,432	1,108,224
Government agency and government-sponsored enterprise collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	1,102,097	1,136,397
Private label collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	97,862	99,483
Collateralized loan obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	130,082	123,756
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	733,884	735,159
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	5,378	5,181
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	210,699	214,783
SBA asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	45,441	48,258
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	16,957	20,748
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	3,757,663
Equity warrants	4,290	3,434
Other derivative assets	4,946	1,234
Derivative liabilities	1,152	755
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	5,378	5,181
Equity warrants	0	0
Other derivative assets	0	0
Equity Securities, FV-NI	2,471	2,998
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	3,732,724	3,769,307
Equity warrants	0	0
Other derivative assets	4,946	1,234
Equity Securities, FV-NI	0	0
Derivative liabilities	1,152	755
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale, at fair value	19,561	22,699
Equity warrants	4,290	3,434
Other derivative assets	0	0
Equity Securities, FV-NI	0	0
Derivative liabilities	0	0
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	289,831	305,198
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	289,831	305,198
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	1,102,097	1,136,397
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	1,102,097	1,136,397
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
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	97,862	99,483
Fair Value, Measurements, Recurring | Private label collateralized mortgage obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Private label collateralized mortgage obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	92,920	93,219
Fair Value, Measurements, Recurring | Private label collateralized mortgage obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	4,942	6,264
Fair Value, Measurements, Recurring | Collateralized loan obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	130,082	123,756
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	130,082	123,756
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	733,884	735,159
Fair Value, Measurements, Recurring | Municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	733,884	735,159
Fair Value, Measurements, Recurring | Municipal securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	1,125,432	1,108,224
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	1,125,432	1,108,224
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
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	5,378	5,181
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	5,378	5,181
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	210,699	214,783
Fair Value, Measurements, Recurring | Asset-backed Securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Asset-backed Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	196,080	198,348
Fair Value, Measurements, Recurring | Asset-backed Securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	14,619	16,435
Fair Value, Measurements, Recurring | SBA asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	45,441	48,258
Fair Value, Measurements, Recurring | SBA asset-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | SBA asset-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	45,441	48,258
Fair Value, Measurements, Recurring | SBA asset-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	16,957	20,748
Fair Value, Measurements, Recurring | Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	16,957	20,748
Fair Value, Measurements, Recurring | Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available‑for‑sale	$ 0	$ 0