Property and Casualty Unpaid Claims and Claim Expenses - Summary of Reinsurance Reserve Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Beginning Gross reserves	$ 396,714
Claims and claim expense payments for claims occurring during:
Ending Gross reserves	393,549
Benefits, claims and settlement expenses	139,384	$ 143,562
Property and Casualty
Segment Reporting Information [Line Items]
Beginning Gross reserves	367,180	319,182
Less: reinsurance recoverables	89,725	57,409
Net reserves, beginning of year	277,455	261,773
Incurred claims and claim expenses:
Claims occurring in the current period	118,767	120,988
Decrease in estimated reserves for claims occurring in prior years	(2,000)	(300)
Total claims and claim expenses incurred	116,767	120,688
Claims and claim expense payments for claims occurring during:
Current period	45,714	47,048
Prior periods	67,135	67,075
Total claims and claim expense payments	112,849	114,123
Net reserves, end of year	281,373	268,338
Plus: reinsurance recoverables	78,328	62,917
Ending Gross reserves	359,701	331,255
Life and Annuity segments
Claims and claim expense payments for claims occurring during:
Net reserves, end of year	33,848	27,062
Benefits, claims and settlement expenses	$ 22,617	$ 22,874