Investment Securities - Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
Due in one year or less	$ 453
Due after one year through five years	49,599
Due after five years through ten years	144,692
Due after ten years	212,595
Total excluding mortgage-backed securities	407,339
Mortgage-backed securities	539,172
Amortized Cost	946,511	$ 372,231
Fair Value
Due in one year or less	453
Due after one year through five years	49,622
Due after five years through ten years	143,011
Due after ten years	210,807
Total excluding mortgage-backed securities	403,893
Mortgage-backed securities	534,271
Investment securities available for sale	$ 938,164	$ 380,814

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563