Debt Securities Held to Maturity Narrative (Details)	3 Months Ended
Mar. 31, 2019 USD ($) security	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) security
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	$ 287,529,000		$ 262,143,000
Fair value	284,450,000		254,841,000
Proceeds from sale of held-to-maturity securities	0	$ 0
Fair value of securities pledged as collateral	$ 222,700,000		$ 187,000,000
Number of positions \| security	76		88
Other-than-temporary impairment loss, held-to-maturity, before tax	$ 0	$ 0
Mortgage-backed securities and collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	254,123,000		$ 238,739,000
Fair value	$ 251,023,000		$ 231,600,000

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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Amount of restricted investment in debt security measured at amortized cost (held-to-maturity).

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Amount, before tax, of other-than-temporary impairment (OTTI) on investment in debt security measured at amortized cost (held-to-maturity), recognized in earnings and other comprehensive income (OCI).

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The cash inflow associated with the sale of securities that had been designated as held-to-maturity. Excludes proceeds from maturities, prepayments and calls by the issuer.

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