Investments - Aggregate Fair Value and Gross Unrealized Loss in Continuous Unrealized Loss Position (Details)	Mar. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security	Mar. 31, 2019 USD ($)
Fair Value
Less Than 12 Months	$ 5,111,000	$ 3,387,000
12 Months or Longer	0	0
Total	5,111,000	3,387,000
Unrealized Loss
Less Than 12 Months	(38,000)	(8,000)
12 Months or Longer	0	0
Total	(38,000)	(8,000)
Credit losses recognized in earnings	0		$ 0
Available-for-sale securities	$ 11,236,000	$ 9,306,000
Number of securities in unrealized loss position for less than 12 months | security	10	5
Number of securities in unrealized loss position for more than 12 months | security	0	0
Municipal bonds
Fair Value
Less Than 12 Months	$ 1,276,000	$ 3,387,000
12 Months or Longer	0	0
Total	1,276,000	3,387,000
Unrealized Loss
Less Than 12 Months	(3,000)	(8,000)
12 Months or Longer	0	0
Total	$ (3,000)	$ (8,000)
Number of portfolio securities | security	9	8
Available-for-sale securities	$ 4,307,000	$ 3,370,000
Agency mortgage-backed securities
Fair Value
Less Than 12 Months	3,835,000
12 Months or Longer	0
Total	3,835,000
Unrealized Loss
Less Than 12 Months	(35,000)
12 Months or Longer	0
Total	$ (35,000)
Number of portfolio securities | security	14	13
Available-for-sale securities	$ 6,929,000	$ 5,936,000