Debt Securities Held to Maturity - Continuous Unrealized Loss Position of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	$ 37,845	$ 11,265
Less than 12 months, Gross unrealized (losses)	(317)	(69)
12 months or longer, Fair value	772	221,443
12 months or longer, Gross unrealized (losses)	(8)	(7,306)
Total, Fair value	38,617	232,708
Total, Gross unrealized (losses)	(325)	(7,375)
U.S. government and agency obligations
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	9,934	0
Less than 12 months, Gross unrealized (losses)	(66)	0
12 months or longer, Fair value	0	8,197
12 months or longer, Gross unrealized (losses)	0	(208)
Total, Fair value	9,934	8,197
Total, Gross unrealized (losses)	(66)	(208)
Mortgage-backed securities and collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	27,911	11,265
Less than 12 months, Gross unrealized (losses)	(251)	(69)
12 months or longer, Fair value	772	213,246
12 months or longer, Gross unrealized (losses)	(8)	(7,098)
Total, Fair value	28,683	224,511
Total, Gross unrealized (losses)	$ (259)	$ (7,167)

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 6
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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

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