Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Amortized Cost
Held to maturity, amortized cost, total	$ 747,004	$ 638,640
Fair Value
Held to maturity, fair value, total	709,492	627,398
Amortized Cost
Available for sale, amortized cost, total	1,802,563	1,653,658
Fair Value
Available for sale, fair value, total	1,706,619	1,644,319
Other debt
Amortized Cost
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
Fair Value
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
Amortized Cost
Available for sale, amortized cost, due in less than one year	2,776
Available for sale, amortized cost, due after one year through five years	14,493
Available for sale, amortized cost, due after five years through ten years	5,705
Available for sale, amortized cost, due after ten years	14,799
Available for sale, amortized cost, total	37,773
Fair Value
Available for sale, fair value, due in less than one year	2,790
Available for sale, fair value, due after one year through five years	14,807
Available for sale, fair value, due after five years through ten years	5,698
Available for sale, fair value, due after ten years	14,234
Available for sale, fair value, total	37,529
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Amortized Cost
Held to maturity, amortized cost, total	747,004
Fair Value
Held to maturity, fair value, total	709,492	627,398
Amortized Cost
Available for sale, amortized cost, total	1,335,336	1,234,721
Fair Value
Available for sale, fair value, total	1,244,670	1,222,720
Private mortgage-backed securities and collateralized mortgage obligations
Amortized Cost
Held to maturity, amortized cost, total	0
Fair Value
Held to maturity, fair value, total	0
Amortized Cost
Available for sale, amortized cost, total	114,286	88,096
Fair Value
Available for sale, fair value, total	111,296	88,767
Collateralized loan obligations
Amortized Cost
Held to maturity, amortized cost, total	0
Fair Value
Held to maturity, fair value, total	0
Amortized Cost
Available for sale, amortized cost, total	315,168	292,751
Fair Value
Available for sale, fair value, total	$ 313,124	$ 292,690