Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 0	$ 1,422	$ 13	$ 4,539
Transfers out of Level 3				3,100
Purchases	0	0	0	0
Sales	0	(62)	(13)	(79)
Included in earnings and reported as losses incurred, net	0	0	0	0
Balance at end of period	0	1,360	0	1,360
Fixed income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	0	254	13	271
Transfers out of Level 3				0
Purchases	0	0	0	0
Sales	0	(62)	(13)	(79)
Included in earnings and reported as losses incurred, net	0	0	0	0
Balance at end of period	0	192	0	192
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	0	1,168	0	4,268
Transfers out of Level 3				3,100
Purchases	0	0	0	0
Sales	0	0	0	0
Included in earnings and reported as losses incurred, net	0	0	0	0
Balance at end of period	0	1,168	0	1,168
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	11,639	10,078	14,535	12,713
Transfers out of Level 3				0
Purchases	7,107	10,869	15,191	16,763
Sales	(8,152)	(6,630)	(19,024)	(15,500)
Included in earnings and reported as losses incurred, net	(344)	(996)	(452)	(655)
Balance at end of period	$ 10,250	$ 13,321	$ 10,250	$ 13,321