Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Beginning gross reserves	$ 442,854
Claims and claim expense payments for claims occurring during:
Ending gross reserves	438,403
Benefits, claims and settlement expenses	138,660	$ 139,384
Property and Casualty
Segment Reporting Information [Line Items]
Beginning gross reserves	386,976	367,180
Less: reinsurance recoverables	120,506	89,725
Net reserves, beginning of period	266,470	277,455
Incurred claims and claim expenses:
Claims occurring in the current period	105,454	118,767
Decrease in estimated reserves for claims occurring in prior periods	(1,000)	(2,000)
Total claims and claim expenses incurred	104,454	116,767
Claims and claim expense payments for claims occurring during:
Current period	43,463	45,714
Prior periods	64,258	67,135
Total claims and claim expense payments	107,721	112,849
Net reserves, end of period	263,203	281,373
Plus: reinsurance recoverables	119,045	78,328
Ending gross reserves	382,248	359,701
Life and Annuity Segments
Claims and claim expense payments for claims occurring during:
Net reserves, end of period	56,200	33,800
Benefits, claims and settlement expenses	$ 34,200	$ 22,600