Schedule III and VI Supplementary Insurance Information Supplemental Information Concerning Property and Casualty Insurance Operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplementary Insurance Information by Segment
Deferred policy acquisition costs	$ 215,082	$ 245,355	$ 196,885
Future policy benefits, claims and claims expenses	5,128,055	4,808,079	4,523,386
Discount, if any, deducted in previous column	0	0	0
Unearned premiums	223,413	221,114	213,268
Other policy claims and benefits payable	606,738	346,292	103,227
Premium revenue/ premium earned	715,760	690,938	670,527
Net investment income	329,815	313,610	306,003
Benefits, claims and settlement expenses	644,565	618,210	611,815
Claims and claims adjustment expense incurred related to current year	0	0	0
Claims and claims adjustment expense incurred related to prior years	0	0	0
Amortization of deferred policy acquisition costs	93,817	84,643	79,519
Other operating expenses	176,190	174,348	170,307
Paid claims and claims adjustment expense	0	0	0
Premiums written	0	0	0
Property and casualty segment [Member]
Supplementary Insurance Information by Segment
Deferred policy acquisition costs	27,160	26,048	24,650
Future policy benefits, claims and claims expenses	311,097	275,809	274,542
Discount, if any, deducted in previous column	0	0	0
Unearned premiums	220,406	217,841	209,431
Other policy claims and benefits payable	0	0	0
Premium revenue/ premium earned	581,828	561,954	546,339
Net investment income	36,790	36,208	36,792
Benefits, claims and settlement expenses	399,512	385,601	389,430
Claims and claims adjustment expense incurred related to current year	416,512	403,589	406,605
Claims and claims adjustment expense incurred related to prior years	(17,000)	(17,988)	(17,175)
Amortization of deferred policy acquisition costs	71,327	68,516	63,768
Other operating expenses	88,305	87,064	83,579
Paid claims and claims adjustment expense	393,857	384,736	398,210
Premiums written	584,393	570,363	550,774
Annuity [Member]
Supplementary Insurance Information by Segment
Deferred policy acquisition costs	143,522	170,749	125,437
Future policy benefits, claims and claims expenses	3,781,260	3,523,901	3,264,128
Discount, if any, deducted in previous column	0	0	0
Unearned premiums	708	562	526
Other policy claims and benefits payable	603,267	342,795	99,603
Premium revenue/ premium earned	25,540	22,575	21,794
Net investment income	222,071	208,419	200,785
Benefits, claims and settlement expenses	134,760	128,768	124,693
Claims and claims adjustment expense incurred related to current year	0	0	0
Claims and claims adjustment expense incurred related to prior years	0	0	0
Amortization of deferred policy acquisition costs	14,781	7,957	6,868
Other operating expenses	33,210	34,004	34,148
Paid claims and claims adjustment expense	0	0	0
Premiums written	0	0	0
Life [Member]
Supplementary Insurance Information by Segment
Deferred policy acquisition costs	44,400	48,558	46,798
Future policy benefits, claims and claims expenses	1,035,698	1,008,369	984,716
Discount, if any, deducted in previous column	0	0	0
Unearned premiums	2,299	2,711	3,311
Other policy claims and benefits payable	3,471	3,497	3,624
Premium revenue/ premium earned	108,392	106,409	102,394
Net investment income	71,865	69,932	69,409
Benefits, claims and settlement expenses	110,293	103,841	97,692
Claims and claims adjustment expense incurred related to current year	0	0	0
Claims and claims adjustment expense incurred related to prior years	0	0	0
Amortization of deferred policy acquisition costs	7,709	8,170	8,883
Other operating expenses	36,421	34,394	33,589
Paid claims and claims adjustment expense	0	0	0
Premiums written	0	0	0
Other, including consolidating eliminations [Member]
Supplementary Insurance Information by Segment
Discount, if any, deducted in previous column	0	0	0
Net investment income	(911)	(949)	(983)
Claims and claims adjustment expense incurred related to current year	0	0	0
Claims and claims adjustment expense incurred related to prior years	0	0	0
Other operating expenses	18,254	18,886	18,991
Paid claims and claims adjustment expense	0	0	0
Premiums written	$ 0	$ 0	$ 0