Investment Securities - Securities With Unrealized Losses (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Available-for-sale
Available-for-sale debt securities, less than 12 months, estimated fair value	$ 502,386
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(1,602)
Available-for-sale debt securities, 12 months or more, estimated fair value	56,895
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(882)
Available-for-sale debt securities, estimated fair value	559,281
Available-for-sale debt securities, gross unrealized losses	(2,484)
U.S. Government agencies
Available-for-sale
Available-for-sale debt securities, less than 12 months, estimated fair value	228,241
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(432)
Available-for-sale debt securities, 12 months or more, estimated fair value	52,853
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(868)
Available-for-sale debt securities, estimated fair value	281,094
Available-for-sale debt securities, gross unrealized losses	(1,300)
Mortgage-backed securities
Available-for-sale
Available-for-sale debt securities, less than 12 months, estimated fair value	264,843
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(1,082)
Available-for-sale debt securities, 12 months or more, estimated fair value	3,703
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(12)
Available-for-sale debt securities, estimated fair value	268,546
Available-for-sale debt securities, gross unrealized losses	(1,094)
State and political subdivisions
Available-for-sale
Available-for-sale debt securities, less than 12 months, estimated fair value	9,302
Available-for-sale debt securities, less than 12 months, gross unrealized losses	(88)
Available-for-sale debt securities, 12 months or more, estimated fair value	339
Available-for-sale debt securities, 12 months or more, gross unrealized losses	(2)
Available-for-sale debt securities, estimated fair value	9,641
Available-for-sale debt securities, gross unrealized losses	$ (90)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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