Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Beginning gross reserves			$ 442,854
Claims and claim expense payments for claims occurring during:
Ending gross reserves	$ 454,516		454,516
Benefits, claims and settlement expenses	151,425	$ 154,191	433,095	$ 446,267
Property and Casualty
Segment Reporting Information [Line Items]
Beginning gross reserves	388,491	367,862	386,976	367,180
Less: reinsurance recoverables	116,083	77,345	120,506	89,725
Net reserves, beginning of period	272,408	290,517	266,470	277,455
Incurred claims and claim expenses:
Claims occurring in the current period	125,622	122,470	340,243	375,648
Decrease in estimated reserves for claims occurring in prior periods	(7,200)	(3,500)	(9,200)	(7,500)
Total claims and claim expenses incurred	118,422	118,970	331,043	368,148
Claims and claim expense payments for claims occurring during:
Current period	91,008	101,499	195,891	230,968
Prior periods	19,280	29,747	121,080	136,394
Total claims and claim expense payments	110,288	131,246	316,971	367,362
Ending gross reserves	395,315	354,767	395,315	354,767
Plus: reinsurance recoverables	114,773	76,526	114,773	76,526
Net reserves, end of period	280,542	278,241	280,542	278,241
Life and Annuity Segments
Claims and claim expense payments for claims occurring during:
Net reserves, end of period	59,200	57,500	59,200	57,500
Benefits, claims and settlement expenses	$ 33,000	$ 35,200	$ 102,100	$ 78,100