Schedule III and VI Supplementary Insurance Information Supplemental Information Concerning Property and Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	$ 229,828	$ 276,668	$ 298,742
Future policy benefits, claims and claim expenses	6,884,077	6,677,306	6,107,907
Unearned premiums	264,489	279,163	276,225
Other policy claims and benefits payable	751,296	647,283	767,988
Premium revenue/ premium earned	930,697	897,954	817,333
Net investment income	357,596	365,064	376,507
Benefits, claims and settlement expenses	773,526	797,854	843,759
Amortization of deferred policy acquisition costs	99,909	109,181	109,889
Other operating expenses	277,423	287,001	218,414
Property and Casualty
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	26,153	28,616	30,033
Future policy benefits, claims and claim expenses	372,154	386,976	367,180
Discount, if any, deducted in previous column	0	0	0
Unearned premiums	259,356	273,998	274,351
Other policy claims and benefits payable	0	0	0
Premium revenue/ premium earned	650,168	683,454	665,734
Net investment income	42,556	41,740	40,104
Benefits, claims and settlement expenses	430,991	475,563	547,659
Claims and claims adjustment expense incurred related to current year	441,191	483,062	547,959
Claims and claims adjustment expense incurred related to prior years	(10,200)	(7,500)	(300)
Amortization of deferred policy acquisition costs	74,452	79,453	79,073
Other operating expenses	97,716	105,489	101,834
Paid claims and claim adjustment expenses	438,189	486,547	531,977
Premiums written	635,525	683,101	681,583
Supplemental
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	4,270	1,967
Future policy benefits, claims and claim expenses	392,362	390,276
Unearned premiums	3,084	3,218
Other policy claims and benefits payable	41,514	0
Premium revenue/ premium earned	130,694	65,815
Net investment income	17,818	7,480
Benefits, claims and settlement expenses	43,166	24,723
Amortization of deferred policy acquisition costs	1,287	438
Other operating expenses	51,686	26,476
Retirement
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	137,735	185,294	209,232
Future policy benefits, claims and claim expenses	4,874,167	4,698,461	4,573,170
Unearned premiums	716	734	704
Other policy claims and benefits payable	706,297	643,826	764,607
Premium revenue/ premium earned	29,649	29,083	31,269
Net investment income	229,853	245,475	262,634
Benefits, claims and settlement expenses	164,807	173,116	168,732
Amortization of deferred policy acquisition costs	16,718	21,446	23,186
Other operating expenses	72,093	90,782	57,269
Life
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	61,670	60,791	59,477
Future policy benefits, claims and claim expenses	1,245,394	1,201,593	1,167,557
Unearned premiums	1,333	1,213	1,170
Other policy claims and benefits payable	3,485	3,457	3,381
Premium revenue/ premium earned	120,186	119,602	120,330
Net investment income	69,799	71,957	74,399
Benefits, claims and settlement expenses	134,562	124,452	127,368
Amortization of deferred policy acquisition costs	7,452	7,844	7,630
Other operating expenses	35,292	37,820	36,314
Other, including consolidating eliminations | Eliminations
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Net investment income	(2,430)	(1,588)	(630)
Other operating expenses	$ 20,636	$ 26,434	$ 22,997