Available-for-Sale Securities - Additional Information (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) Security
Schedule Of Available For Sale Securities [Line Items]
Held to maturity	$ 0		$ 0		$ 0
Sale of available-for-sale securities	$ 0	$ 3,748,000	0	$ 3,748,000
Purchases of available-for-sale securities			$ 30,000,000
Number of available for sale securities \| Security	12		12		12
Number of investment securities not other than temporary \| Security	11		11		11
Securities pledged	$ 0		$ 0		$ 0
U S Treasury
Schedule Of Available For Sale Securities [Line Items]
Purchases of available-for-sale securities	$ 30,000,000

Investment portfolio number of available for sale securities.

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- Definition

Sales of available for sale securities.

+ References

No definition available.

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- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

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-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 6
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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of cash outflow to acquire investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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