SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Statements of Earnings and Comprehensive Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONDENSED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS
Net investment income	$ 13,754	$ 13,964	$ 13,431	$ 13,495	$ 13,844	$ 14,200	$ 13,982	$ 13,582	$ 54,644	$ 55,608	$ 52,763
Net realized gains (losses)	14,207	7,534	4,802	13,286	9,542	5,708	10,431	6,501	39,829	32,182	22,036
Equity in earnings of unconsolidated investees									10,914	12,338	10,915
Interest expense on debt									(7,426)	(7,438)	(8,095)
Loss before income taxes	45,582	51,937	54,650	44,513	46,479	48,594	52,423	41,991	196,682	189,487	175,666
Income tax benefit									59,138	54,042	49,411
Net earnings	$ 33,853	$ 35,908	$ 37,185	$ 30,598	$ 37,497	$ 33,254	$ 35,725	$ 28,969	137,544	135,445	126,255
Unrealized gains (losses) on securities:
Other comprehensive earnings (loss), net of tax									(47,609)	35,356	(7,143)
Comprehensive earnings									89,935	170,801	119,112
PARENT COMPANY
CONDENSED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS
Net investment income									810	663	652
Net realized gains (losses)									139	271	(850)
Equity in earnings of unconsolidated investees									9,893	12,009	10,915
Selling, general and administrative expenses									(9,837)	(10,222)	(8,746)
Interest expense on debt									(7,426)	(7,438)	(8,095)
Loss before income taxes									(6,421)	(4,717)	(6,124)
Income tax benefit									(5,499)	(7,959)	(11,946)
Net earnings (loss) before equity in net earnings of subsidiaries									(922)	3,242	5,822
Equity in net earnings of subsidiaries									138,466	132,203	120,433
Net earnings									137,544	135,445	126,255
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period									(40)	372	(665)
Less: reclassification adjustment for losses (gains) included in net earnings									(90)	(176)
Other Comprehensive Income (Loss), Net of Tax, Total									(130)	196	(665)
Equity in other comprehensive earnings (loss) of subsidiaries/investees									(47,479)	35,160	(6,478)
Other comprehensive earnings (loss), net of tax									(47,609)	35,356	(7,143)
Comprehensive earnings									$ 89,935	$ 170,801	$ 119,112