Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Summarized financial information for these segments
Insurance premiums and contract charges earned	$ 185,450	$ 179,739
Net investment income	84,659	83,313
Net income (loss)	25,153	34,275
Assets	10,231,387		$ 10,056,972
Intersegment Eliminations [Member]
Summarized financial information for these segments
Net investment income	(217)	(226)
Assets	(39,151)		(37,208)
Property and casualty [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	152,120	146,749
Net investment income	8,828	9,433
Net income (loss)	13,795	17,623
Assets	1,124,591		1,098,415
Annuity [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	6,068	6,223
Net investment income	58,049	56,392
Net income (loss)	10,553	12,510
Assets	7,105,367		7,001,411
Life [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	27,262	26,767
Net investment income	17,984	17,708
Net income (loss)	3,867	3,385
Assets	1,914,326		1,862,719
Corporate and other [Member]
Summarized financial information for these segments
Net investment income	15	6
Net income (loss)	(3,062)	$ 757
Assets	$ 126,254		$ 131,635