Debt Securities Held-to-maturity - Aggregate Amortized Cost and Fair Value of HTMS by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Held-to-maturity Securities, Classified [Abstract]
Amortized cost - Within 1 year	$ 3,990
Amortized cost - After 1 to 5 years	16,061
Amortized cost - After 5 to 10 years	14,845
Amortized cost - After 10 years	57,725
Amortized Cost	92,621	$ 97,662
Fair Value - within 1 year	3,987
Fair Value - After 1 to 5 years	16,062
Fair Value - After 5 to 10 years	14,544
Fair Value - After 10 years	60,298
Fair value	$ 94,891	$ 105,110

Amount 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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amount 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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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