Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Total fixed income securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 0	$ 13
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as losses incurred, net	0	0
Acquisitions	0	0
Sales	0	(13)
Balance at end of period	0	0
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	7,252	14,535
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as losses incurred, net	660	(476)
Acquisitions	8,609	24,204
Sales	(15,429)	(31,011)
Balance at end of period	$ 1,092	$ 7,252