Securities - Schedule of Held-to-Maturity Securities Amortized Cost and Estimated Fair Value (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Amortized Cost
Due after five years through ten years	$ 269,268,000
Total held-to-maturity debt securities	269,268,000	$ 0
Fair Value
Due after five years through ten years	268,283,000
Total held-to-maturity debt securities	$ 268,283,000	$ 0

Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), 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).

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