Debt Securities Held to Maturity Narrative (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2019 USD ($) security	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) security	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) security
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	$ 299,605,000		$ 299,605,000		$ 262,143,000
Fair value	303,179,000		303,179,000		254,841,000
Proceeds from sale of held-to-maturity securities	$ 0	$ 0	$ 0	$ 0
Number of debt securities called \| security	1		1
Proceeds from sale and maturity of held-to-maturity securities	$ 5,000,000		$ 5,000,000
Debt securities, held-to-maturity, sold, realized gain (loss)	0		0
Fair value of securities sold under agreements to repurchase	$ 198,600,000		$ 198,600,000		$ 187,000,000
Number of positions \| security	46		46		88
Other-than-temporary impairment loss, held-to-maturity, before tax	$ 0	$ 0	$ 0	$ 0
Mortgage-backed securities and collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Debt securities, held-to-maturity	261,199,000		261,199,000		$ 238,739,000
Fair value	$ 264,658,000		$ 264,658,000		$ 231,600,000

Debt Securities, Held-to-maturity, Number Of Debt Securities Called

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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).

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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 gain (loss) on sale of investment in debt security measured at amortized cost (held-to-maturity), including other-than-temporary impairment (OTTI).

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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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Amount of cash inflow from the sale or maturity of long-term held-to-maturity securities.

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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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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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