Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Beginning Gross reserves			$ 396,714
Claims and claim expense payments for claims occurring during:
Ending Gross reserves	$ 412,272		412,272
Benefits, claims and settlement expenses	154,191	$ 161,846	446,267	$ 473,686
Property and Casualty
Segment Reporting Information [Line Items]
Beginning Gross reserves	367,862	352,817	367,180	319,182
Less: reinsurance recoverables	77,345	62,883	89,725	57,409
Net reserves, beginning of year	290,517	289,934	277,455	261,773
Incurred claims and claim expenses:
Claims occurring in the current period	122,470	140,035	375,648	408,028
Decrease in estimated reserves for claims occurring in prior years	(3,500)	0	(7,500)	(300)
Total claims and claim expenses incurred	118,970	140,035	368,148	407,728
Claims and claim expense payments for claims occurring during:
Current period	101,499	106,187	230,968	233,638
Prior periods	29,747	28,997	136,394	141,078
Total claims and claim expense payments	131,246	135,184	367,362	374,716
Net reserves, end of year	278,241	294,785	278,241	294,785
Plus: reinsurance recoverables	76,526	63,262	76,526	63,262
Ending Gross reserves	354,767	358,047	354,767	358,047
Life and Annuity segments
Claims and claim expense payments for claims occurring during:
Net reserves, end of year	57,505	26,589	57,505	26,589
Benefits, claims and settlement expenses	$ 35,221	$ 21,811	$ 78,119	$ 65,958