Investment Securities - Debt Maturities (Details) - Investment securities: $ in Thousands	Dec. 31, 2021 USD ($)
Amortized Cost
Due within one year	$ 646,946
Due after one year through five years	812,878
Due after five years through ten years	1,712,906
Due after ten years	661,984
Debt securities, available-for-sale, amortized cost	3,834,714
Fair Value
Due within one year	646,518
Due after one year through five years	810,767
Due after five years through ten years	1,710,515
Due after ten years	668,591
Total, Fair Value	$ 3,836,391
Weighted- Average Yield
Due within one year	1.23%
Due after one year through five years	0.42%
Due after five years through ten years	0.88%
Due after ten years	0.64%
Total, Weighted-Average Yield	0.80%