Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Summarized financial information for these segments
Insurance premiums and contract charges earned	$ 195,722	$ 185,450
Net investment income	90,711	84,659
Net income (loss)	15,318	25,153
Assets	10,779,505		$ 10,576,824
Intersegment eliminations [Member]
Summarized financial information for these segments
Net investment income	(208)	(217)
Assets	(28,453)		(36,786)
Property and casualty [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	158,318	152,120
Net investment income	9,177	8,828
Net income (loss)	2,735	13,795
Assets	1,117,764		1,110,958
Retirement [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	6,601	6,068
Net investment income	63,442	58,049
Net income (loss)	11,530	10,553
Assets	7,622,077		7,449,777
Life [Member]
Summarized financial information for these segments
Insurance premiums and contract charges earned	30,803	27,262
Net investment income	18,288	17,984
Net income (loss)	3,885	3,867
Assets	1,941,372		1,912,771
Corporate and Other [Member]
Summarized financial information for these segments
Net investment income	12	15
Net income (loss)	(2,832)	$ (3,062)
Assets	$ 126,745		$ 140,104