Schedule II Condensed Financial Information of Registrant (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Net investment income													$ 329,815	$ 313,610	$ 306,003
Realized investment gains													10,917	22,245	27,298
Total revenues	269,157	265,520	264,743	261,265	259,215	251,884	265,637	254,531	255,417	256,548	254,226	244,623	1,060,685	1,031,267	1,010,814
Expenses
Interest													14,198	14,236	14,249
Total expenses													914,572	877,201	861,641
Income tax benefit													41,870	43,173	45,307
Net income	30,068	25,357	20,452	28,366	34,287	23,599	25,995	27,012	31,826	32,266	13,103	26,671	104,243	110,893	103,866
Parent Company [Member]
Revenues
Net investment income													10	6	2
Realized investment gains													0	208	0
Total revenues													10	214	2
Expenses
Interest													14,198	14,236	14,249
Other													5,071	4,832	4,576
Total expenses													19,269	19,068	18,825
Loss before income tax benefit and equity in net earnings of subsidiaries													(19,259)	(18,854)	(18,823)
Income tax benefit													(6,734)	(6,599)	(6,196)
Loss before equity in net earnings of subsidiaries													(12,525)	(12,255)	(12,627)
Equity in net earnings of subsidiaries													116,768	123,148	116,493
Net income													$ 104,243	$ 110,893	$ 103,866