Fair Value of Financial Instruments - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Level 1
Financial assets
Derivative asset	$ 0	$ 0
Financial liabilities
Derivative liability	0	0
Level 2
Financial assets
Derivative asset	12,053	2,103
Financial liabilities
Derivative liability	12,066	2,103
Level 3
Financial assets
Derivative asset	1,914	0
Financial liabilities
Derivative liability	0	0
Fair Value, Recurring
Financial assets
Securities available for sale:	3,931,115	1,368,384
Derivative asset	13,967	2,103
Financial liabilities
Derivative liability	12,066	2,103
Fair Value, Recurring | Interest rate swap contracts
Financial assets
Derivative asset	12,053
Fair Value, Recurring | Equity warrants
Financial assets
Derivative asset	1,914
Fair Value, Recurring | U.S. Treasury
Financial assets
Securities available for sale:	32,533	63,555
Fair Value, Recurring | Agency
Financial assets
Securities available for sale:	690,386	246,358
Fair Value, Recurring | Corporate debt
Financial assets
Securities available for sale:	415,308	151,353
Fair Value, Recurring | Municipal bonds
Financial assets
Securities available for sale:	1,446,019	397,298
Fair Value, Recurring | Collateralized mortgage obligations
Financial assets
Securities available for sale:	513,366	9,984
Fair Value, Recurring | Mortgage-backed securities
Financial assets
Securities available for sale:	833,503	499,836
Fair Value, Recurring | Level 1
Financial assets
Securities available for sale:	0	0
Derivative asset	0	0
Financial liabilities
Derivative liability	0	0
Fair Value, Recurring | Level 1 | Interest rate swap contracts
Financial assets
Derivative asset	0
Fair Value, Recurring | Level 1 | Equity warrants
Financial assets
Derivative asset	0
Fair Value, Recurring | Level 1 | U.S. Treasury
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 1 | Agency
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 1 | Corporate debt
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 1 | Municipal bonds
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 1 | Collateralized mortgage obligations
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 1 | Mortgage-backed securities
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 2
Financial assets
Securities available for sale:	3,931,115	1,368,384
Derivative asset	12,053	2,103
Financial liabilities
Derivative liability	12,066	2,103
Fair Value, Recurring | Level 2 | Interest rate swap contracts
Financial assets
Derivative asset	12,053
Fair Value, Recurring | Level 2 | Equity warrants
Financial assets
Derivative asset	0
Fair Value, Recurring | Level 2 | U.S. Treasury
Financial assets
Securities available for sale:	32,533	63,555
Fair Value, Recurring | Level 2 | Agency
Financial assets
Securities available for sale:	690,386	246,358
Fair Value, Recurring | Level 2 | Corporate debt
Financial assets
Securities available for sale:	415,308	151,353
Fair Value, Recurring | Level 2 | Municipal bonds
Financial assets
Securities available for sale:	1,446,019	397,298
Fair Value, Recurring | Level 2 | Collateralized mortgage obligations
Financial assets
Securities available for sale:	513,366	9,984
Fair Value, Recurring | Level 2 | Mortgage-backed securities
Financial assets
Securities available for sale:	833,503	499,836
Fair Value, Recurring | Level 3
Financial assets
Securities available for sale:	0	0
Derivative asset	1,914	0
Financial liabilities
Derivative liability	0	0
Fair Value, Recurring | Level 3 | Interest rate swap contracts
Financial assets
Derivative asset	0
Fair Value, Recurring | Level 3 | Equity warrants
Financial assets
Derivative asset	1,914
Fair Value, Recurring | Level 3 | U.S. Treasury
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 3 | Agency
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 3 | Corporate debt
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 3 | Municipal bonds
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 3 | Collateralized mortgage obligations
Financial assets
Securities available for sale:	0	0
Fair Value, Recurring | Level 3 | Mortgage-backed securities
Financial assets
Securities available for sale:	$ 0	$ 0