Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Summarized financial information for these segments
Insurance premiums and contract charges earned	$ 175,403	$ 169,158
Net investment income	83,044	77,403
Net income (loss)	28,366	27,012
Assets	9,083,452		8,826,672
Property and casualty [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	143,892	137,936
Net investment income	9,285	8,970
Net income (loss)	14,027	10,160
Assets	1,044,099		1,001,561
Annuity [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	5,924	5,072
Net investment income	55,857	51,354
Net income (loss)	12,239	11,061
Assets	6,117,855		5,963,348
Life [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	25,587	26,150
Net investment income	18,134	17,319
Net income (loss)	3,882	4,340
Assets	1,809,567		1,743,084
Corporate and other [Member]
Summarized financial information for these segments
Net investment income	2	0
Net income (loss)	(1,782)	1,451
Assets	140,386		154,557
Intersegment eliminations [Member]
Summarized financial information for these segments
Net investment income	(234)	(240)
Assets	$ (28,455)		$ (35,878)