Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning of year	$ 442,854
Less: reinsurance recoverables	129,213
Claims and claim expense payments for claims occurring during:
Plus: reinsurance recoverables	122,450	$ 129,213
Gross reserves, end of year	438,754	442,854
Benefits, claims and settlement expenses	568,891	585,068	$ 637,560
Property and Casualty segment
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning of year	386,976	367,180	319,182
Less: reinsurance recoverables	120,506	89,725	57,409
Net reserves, beginning of year	266,470	277,455	261,773
Incurred claims and claim expenses:
Claims occurring in the current year	441,191	483,062	547,959
Decrease in estimated reserves for claims occurring in prior years	(10,200)	(7,500)	(300)
Total claims and claim expenses incurred	430,991	475,562	547,659
Claims and claim expense payments for claims occurring during:
Current year	291,393	329,475	369,194
Prior years	146,796	157,072	162,783
Total claims and claim expense payments	438,189	486,547	531,977
Net reserves, end of year	259,272	266,470	277,455
Plus: reinsurance recoverables	112,881	120,506	89,725
Gross reserves, end of year	372,153	386,976	367,180
Life and Annuity segments
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves, beginning of year	55,900	29,500
Claims and claim expense payments for claims occurring during:
Net reserves, end of year	66,600	55,900	29,500
Benefits, claims and settlement expenses	$ 137,900	$ 109,500	$ 89,900