Investments, Securities with Continuous Unrealized Loss Position (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) Securities	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Securities	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) Securities
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 21,441		$ 21,441		$ 11,647
12 months or longer	1,923		1,923		0
Total	23,364		23,364		11,647
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	357		357		94
12 months or longer	141		141		0
Total	498		498		$ 94
Gross OTTI losses charged to realized gains	$ 0	$ 0	$ 0	$ 0
Number of securities in unrealized loss position | Securities	30		30		20
U.S. Treasury Securities and Obligations of U.S. Government Agencies and Authorities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 15,275		$ 15,275		$ 7,045
12 months or longer	0		0		0
Total	15,275		15,275		7,045
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	195		195		26
12 months or longer	0		0		0
Total	195		195		26
Corporate Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	6,166		6,166		4,602
12 months or longer	1,923		1,923		0
Total	8,089		8,089		4,602
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	162		162		68
12 months or longer	141		141		0
Total	$ 303		$ 303		$ 68