SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses	$ (11,283)	$ (9,252)	$ (2,710)	$ (11,400)	$ (14,207)	$ (7,534)	$ (4,802)	$ (13,286)	$ (34,645)	$ (39,829)	$ (32,182)
Depreciation									6,430	5,406	4,557
Other items, net									17,699	15,006	10,818
Change in:
Stock option excess tax benefit									(9,576)	(11,413)	(1,766)
Changes in investment in unconsolidated investees:
Undistributed earnings									(10,833)	(10,914)	(12,338)
Dividends received									9,900		6,600
Net cash provided by operating activities									174,463	152,586	123,085
Purchase of:
Fixed income, available-for-sale									(557,067)	(665,422)	(470,210)
Property and equipment									(16,155)	(10,035)	(7,121)
Sale of:
Fixed income, available-for-sale									329,091	436,680	342,308
Short-term investments, net									2,564	6,637	11,401
Property and equipment									1,688	76	276
Call or maturity of:
Fixed income, available-for-sale									141,255	156,980	101,517
Net cash used in investing activities									(53,622)	(60,597)	22,771
Cash flows from financing activities
Stock option excess tax benefit									9,576	11,413	1,766
Proceeds from stock option exercises									(741)	(3,364)	3,386
Net cash used in financing activities									(113,653)	(111,528)	(154,705)
Net (decrease) increase in cash									7,188	(19,539)	(8,849)
Cash at the beginning of the period				11,081				30,620	11,081	30,620	39,469
Cash at the end of the period	18,269				11,081				18,269	11,081	30,620
PARENT COMPANY
Cash flows from operating activities
Earnings (loss) before equity in net earnings of subsidiaries									1,217	(922)	3,242
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses									360	(139)	(271)
Depreciation									196	237	238
Other items, net									560	530	737
Change in:
Affiliate balances receivable/payable									(535)	4,211	(1,453)
Federal income taxes									9,762	14,227	3,982
Stock option excess tax benefit									(9,576)	(11,413)	(1,766)
Changes in investment in unconsolidated investees:
Undistributed earnings									(9,764)	(9,893)	(12,009)
Dividends received									9,900		6,600
Net cash provided by operating activities									2,120	(3,162)	(700)
Purchase of:
Fixed income, available-for-sale									(12,844)	(16,031)	(30,850)
Sale of:
Fixed income, available-for-sale									4,981	7,048
Short-term investments, net									63	91	13,217
Call or maturity of:
Fixed income, available-for-sale									6,859	9,507	3,235
Cash dividends received-subsidiaries									123,600	125,000	185,000
Net cash used in investing activities									122,659	125,615	170,602
Cash flows from financing activities
Stock option excess tax benefit									9,576	11,413	1,766
Proceeds from stock option exercises									(741)	(3,364)	3,386
Cash dividends paid									(133,771)	(130,698)	(174,861)
Net cash used in financing activities									(124,936)	(122,649)	(169,709)
Net (decrease) increase in cash									(157)	(196)	193
Cash at the beginning of the period				$ 178				$ 374	178	374	181
Cash at the end of the period	$ 21				$ 178				21	178	374
Interest paid on outstanding debt									$ 7,300	$ 7,300	$ 7,000