Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Beginning gross reserves			$ 442,854
Claims and claim expense payments for claims occurring during:
Ending gross reserves	$ 444,558		444,558
Benefits, claims and settlement expenses	143,010	$ 152,692	281,670	$ 292,076
Property and Casualty
Segment Reporting Information [Line Items]
Beginning gross reserves	382,248	359,701	386,976	367,180
Less: reinsurance recoverables	119,045	78,328	120,506	89,725
Net reserves, beginning of period	263,203	281,373	266,470	277,455
Incurred claims and claim expenses:
Claims occurring in the current period	109,167	134,411	214,621	253,178
Decrease in estimated reserves for claims occurring in prior periods	(1,000)	(2,000)	(2,000)	(4,000)
Total claims and claim expenses incurred	108,167	132,411	212,621	249,178
Claims and claim expense payments for claims occurring during:
Current period	61,420	83,755	104,883	129,469
Prior periods	37,542	39,512	101,800	106,647
Total claims and claim expense payments	98,962	123,267	206,683	236,116
Ending gross reserves	388,491	367,862	388,491	367,862
Plus: reinsurance recoverables	116,083	77,345	116,083	77,345
Net reserves, end of period	272,408	290,517	272,408	290,517
Life and Annuity Segments
Claims and claim expense payments for claims occurring during:
Net reserves, end of period	56,100	30,500	56,100	30,500
Benefits, claims and settlement expenses	$ 34,800	$ 20,300	$ 69,100	$ 42,900