Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) Security	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Proceeds from calls and principal repayments	$ 8,196,000	$ 11,707,000	$ 12,934,000
Gain on sale of securities	79,000	838,000	0
Fair value of securities purchased	27,600,000	12,400,000	34,200,000
Proceeds from sale of securities, available for sale	$ 13,871,000	0	$ 0
Number of securities | Security	21
Corporate bonds with cost basis net of other-than-temporary impairment	$ 78,144,000	72,958,000
Other than temporary impairment recognized	0
Carrying value of pledged securities	$ 16,600,000	16,500,000
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Face value of corporate bond		4,000,000
Number of securities | Security	1
Corporate bonds with cost basis net of other-than-temporary impairment	$ 680,000	$ 680,000