Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Summarized financial information for these segments
Insurance premiums and contract charges earned	$ 166,335	$ 166,345	$ 331,839	$ 333,031
Net investment income	76,334	71,689	152,009	142,158
Net income (loss)	13,103	(11,851)	39,774	13,956
Assets	7,823,954		7,823,954		7,435,169
Property and casualty [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	135,616	136,455	270,662	273,820
Net investment income	9,356	9,261	18,228	18,475
Net income (loss)	(4,127)	(25,622)	9,104	(13,246)
Assets	1,010,940		1,010,940		957,266
Annuity [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	5,537	4,751	10,502	9,507
Net investment income	49,718	45,213	99,258	89,447
Net income (loss)	7,874	7,315	19,462	15,768
Assets	5,221,087		5,221,087		4,926,204
Life [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	25,182	25,139	50,675	49,704
Net investment income	17,505	17,470	35,017	34,746
Net income (loss)	6,130	5,845	11,295	10,048
Assets	1,506,800		1,506,800		1,459,919
Corporate and other [Member]
Summarized financial information for these segments
Net investment income	1	(1)	1	(1)
Net income (loss)	3,226	611	(87)	1,386
Assets	108,773		108,773		115,367
Intersegment eliminations [Member]
Summarized financial information for these segments
Net investment income	(246)	(254)	(495)	(509)
Assets	$ (23,646)		$ (23,646)		$ (23,587)