Securities - Schedule of Book Values and Fair Values of Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
Due within one year	$ 1,001
Due after one year but within five years	27,629
Due after five years but within ten years	87,701
Due after ten years	1,000
Mortgage-backed securities	2,545,150
Amortized Cost	2,662,481	$ 1,432,684
Fair Value
Due within one year	1,020
Due after one year but within five years	28,454
Due after five years but within ten years	85,191
Due after ten years	944
Mortgage-backed securities	2,514,805
Total securities	2,630,414	1,453,132
Amortized Cost
Due within one year	1,246
Due after one year but within five years	0
Due after five years but within ten years	16,058
Due after ten years	476,261
Mortgage-backed securities	20,260
Amortized Cost	513,825	167,551
Fair Value
Due within one year	1,258
Due after one year but within five years	0
Due after five years but within ten years	16,112
Due after ten years	473,484
Mortgage-backed securities	20,845
Total securities	$ 511,699	$ 170,734