Investments - Security Holdings in an Unrealized Loss Position - General Information (Details) $ in Thousands	Sep. 30, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Number of positions:
Number of unrealized loss positions | security	153	90
Fair Value
Fair Value	$ 112,278	$ 41,525
Unrealized Losses
Unrealized Losses	$ 1,640	$ 513