Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Summarized financial information for these segments
Insurance premiums and contract charges earned	$ 182,376	$ 179,138	$ 362,115	$ 354,541
Net investment income	83,995	81,405	167,308	164,449
Net income (loss)	16,183	20,452	50,458	48,818
Assets	9,969,540		9,969,540		$ 9,768,527
Property and casualty [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	147,657	144,658	294,406	288,550
Net investment income	9,007	9,455	18,440	18,740
Net income (loss)	3,244	4,895	20,867	18,922
Assets	1,110,927		1,110,927		1,107,962
Annuity [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	6,516	6,453	12,739	12,377
Net investment income	57,183	54,338	113,575	110,195
Net income (loss)	11,747	11,573	24,257	23,812
Assets	6,860,029		6,860,029		6,683,473
Life [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	28,203	28,027	54,970	53,614
Net investment income	18,022	17,842	35,730	35,976
Net income (loss)	3,643	5,015	7,028	8,897
Assets	1,886,005		1,886,005		1,858,150
Corporate and other [Member]
Summarized financial information for these segments
Net investment income	6	2	12	4
Net income (loss)	(2,451)	(1,031)	(1,694)	(2,813)
Assets	143,281		143,281		155,678
Intersegment eliminations [Member]
Summarized financial information for these segments
Net investment income	(223)	$ (232)	(449)	$ (466)
Assets	$ (30,702)		$ (30,702)		$ (36,736)