Property and Casualty Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Gross reserves, beginning of year	$ 396,714
Less: reinsurance recoverables	99,510
Claims and claim expense payments for claims occurring during:
Benefits, claims and settlement expenses	585,068	$ 637,560	$ 582,306
Plus: reinsurance recoverables	129,213	99,510
Gross reserves, end of year	442,854	396,714
Property and Casualty segment
Segment Reporting Information [Line Items]
Gross reserves, beginning of year	367,180	319,182	307,757
Less: reinsurance recoverables	89,725	57,409	61,199
Net reserves, beginning of year	277,455	261,773	246,558
Incurred claims and claim expenses:
Claims occurring in the current year	483,062	547,959	498,989
Decrease in estimated reserves for claims occurring in prior years	(7,500)	(300)	(2,700)
Total claims and claim expenses incurred	475,562	547,659	496,289
Claims and claim expense payments for claims occurring during:
Current year	329,475	369,194	333,385
Prior years	157,072	162,783	147,689
Total claims and claim expense payments	486,547	531,977	481,074
Net reserves, end of year	266,470	277,455	261,773
Liability for unpaid claims and claims adjustment expense, net	266,470	261,773	261,773
Plus: reinsurance recoverables	120,506	89,725	57,409
Gross reserves, end of year	386,976	367,180	319,182
Life and Annuity segments
Segment Reporting Information [Line Items]
Net reserves, beginning of year	29,500	28,600
Claims and claim expense payments for claims occurring during:
Net reserves, end of year	55,900	29,500	28,600
Liability for unpaid claims and claims adjustment expense, net	29,500	28,600	28,600
Benefits, claims and settlement expenses	$ 109,500	$ 89,900	$ 86,000