Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	$ 184,484	$ 261,369
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	192,179	262,213
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	1,371,539	940,765
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	1,398,157	946,855
Other debt obligations
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, due in less than one year	0
Held to maturity, amortized cost, due after one year through five years	0
Held to maturity, amortized cost, due after five years through ten years	0
Held to maturity, amortized cost, due after ten years	0
Held to maturity, amortized cost, total	0
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, due in less than one year	0
Held to maturity, fair value, due after one year through five years	0
Held to maturity, fair value, due after five years through ten years	0
Held to maturity, fair value, due after ten years	0
Held to maturity, fair value, total	0
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, due in less than one year	35
Available for sale, amortized cost, due after one year through five years	11,305
Available for sale, amortized cost, due after five years through ten years	8,590
Available for sale, amortized cost, due after ten years	21,325
Available for sale, amortized cost, total	41,255
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, due in less than one year	35
Available for sale, fair value, due after one year through five years	11,929
Available for sale, fair value, due after five years through ten years	9,323
Available for sale, fair value, due after ten years	22,816
Available for sale, fair value, total	44,103
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	184,484
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	192,179	262,213
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	1,038,437	604,934
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	1,060,654	609,207
Private mortgage-backed securities and collateralized mortgage obligations
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	0
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	0
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	89,284	56,005
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	91,205	57,561
Collateralized loan obligations
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	0
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	0
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	202,563	239,364
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	$ 202,195	$ 238,218