Investments - Credit Losses (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cumulative credit loss
Beginning of period	$ 1,529,000	$ 1,529,000
New credit losses	184,000	0
Increases to previously recognized credit losses	0	0
Losses related to securities sold or paid down during the period	(184,000)	0
End of period	1,529,000	$ 1,529,000
Available-for-sale securities, allowance for credit losses	$ 0