SCHEDULE II-CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended
	Mar. 31, 2013	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, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2012	Dec. 31, 2011
ASSETS
Fixed maturities (amortized cost, 2014-$482,629; 2013-$548,528)		$ 4,609,614				$ 4,863,925				$ 4,609,614	$ 4,863,925
Cash and cash equivalents		197,882				332,692				197,882	332,692	1,027,625
Accrued investment income		30,518				31,660				30,518	31,660
Other assets		106,390				141,451				106,390	141,451
Total assets		5,266,434				5,601,390				5,266,434	5,601,390
Liabilities:
Senior notes		61,918				82,773				61,918	82,773
Convertible senior notes		845,000				845,000				845,000	845,000
Convertible junior debentures		389,522				389,522				389,522	389,522
Total liabilities		4,229,531				4,856,852				4,229,531	4,856,852
Shareholders' equity
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2014 and 2013 - 340,047; outstanding 2014 - 338,560; 2013 - 337,758)		340,047				340,047				340,047	340,047
Paid-in capital		1,663,592				1,661,269				1,663,592	1,661,269
Treasury stock (shares at cost 2014, - 1,487; 2013 - 2,289)		(32,937)				(64,435)				(32,937)	(64,435)
Accumulated other comprehensive (loss) income, net of tax		(81,341)				(117,726)				(81,341)	(117,726)	(48,163)
Retained deficit		(852,458)				(1,074,617)				(852,458)	(1,074,617)
Total shareholders' equity		1,036,903				744,538				1,036,903	744,538	196,940		1,196,815
Total liabilities and shareholders' equity		5,266,434				5,601,390				5,266,434	5,601,390
Parenthetical information [Abstract]
Fixed maturities, amortized cost		4,602,514				4,948,543				4,602,514	4,948,543
Common stock, par value (in dollars per share)		$ 1				$ 1				$ 1	$ 1
Common stock, shares authorized (in shares)		1,000,000				1,000,000		680,000		1,000,000	1,000,000		460,000
Common stock, shares issued (in shares)		340,047				340,047				340,047	340,047
Common stock, shares outstanding (in shares)		338,560				337,758				338,560	337,758
Treasury stock, shares at cost (in shares)		1,487				2,289				1,487	2,289
Revenues:
Investment income, net of expenses		23,956	22,355	21,180	20,156	21,278	20,250	20,883	18,328	87,647	80,739	121,640
Realized investment gains, net										1,501	6,059	197,719
Other income		2,385	3,093	2,048	896	2,179	2,481	2,715	2,539	8,422	9,914	28,145
Total revenues										941,797	1,039,435	1,378,364
Expenses:
Interest expense										69,648	79,663	99,344
Total expenses										687,074	1,085,587	2,307,008
Income (loss) before tax										254,723	(46,152)	(928,644)
Benefit from income taxes		681	249	1,118	726	1,231	336	990	1,139	2,774	3,696	(1,565)
Net income (loss)		74,428	72,017	45,522	59,982	(1,407)	12,114	12,375	(72,930)	251,949	(49,848)	(927,079)
Other comprehensive income (loss), net of tax										36,385	(69,563)	(78,287)
Comprehensive income (loss)										288,334	(119,411)	(1,005,366)
Cash flows from operating activities:
Net income (loss)		74,428	72,017	45,522	59,982	(1,407)	12,114	12,375	(72,930)	251,949	(49,848)	(927,079)
Adjustments to reconcile net loss to net cash used in operating activities:
Other										(5,084)	30,077	(21,802)
Change in certain assets and liabilities:
Accrued investment income										1,142	(4,417)	28,423
Cash flows from investing activities:
Purchase of fixed maturities										(1,979,917)	(3,248,602)	(5,025,204)
Sale of fixed maturities										1,147,624	1,054,985	5,216,934
Cash flows from financing activities:
Common stock shares issued	663,300									0	663,335	0
Net (decrease) increase in cash and cash equivalents										(134,810)	(694,933)	31,826
Cash and cash equivalents at beginning of year					332,692				1,027,625	332,692	1,027,625	995,799
Cash and cash equivalents at end of year		197,882				332,692				197,882	332,692	1,027,625
Dividends and Dividend Restrictions [Abstract]
Percentage of statutory policyholders' surplus used to determine maximum allowable dividends (in hundredths)		10.00%								10.00%
Parent Company [Member]
ASSETS
Fixed maturities (amortized cost, 2014-$482,629; 2013-$548,528)		480,125				539,124				480,125	539,124
Cash and cash equivalents		10,507				20,725				10,507	20,725	175,880
Investment in subsidiaries, at equity in net assets		1,821,024				1,475,956				1,821,024	1,475,956
Accounts receivable - affiliates		312				380				312	380
Income taxes receivable		17,478				17,958				17,478	17,958
Accrued investment income		3,435				3,629				3,435	3,629
Other assets		15,156				18,943				15,156	18,943
Total assets		2,348,037				2,076,715				2,348,037	2,076,715
Liabilities:
Senior notes		61,918				82,773				61,918	82,773
Convertible senior notes		845,000				845,000				845,000	845,000
Convertible junior debentures		389,522				389,522				389,522	389,522
Accrued interest		14,694				14,882				14,694	14,882
Total liabilities		1,311,134				1,332,177				1,311,134	1,332,177
Shareholders' equity
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2014 and 2013 - 340,047; outstanding 2014 - 338,560; 2013 - 337,758)		340,047				340,047				340,047	340,047
Paid-in capital		1,663,592				1,661,269				1,663,592	1,661,269
Treasury stock (shares at cost 2014, - 1,487; 2013 - 2,289)		(32,937)				(64,435)				(32,937)	(64,435)
Accumulated other comprehensive (loss) income, net of tax		(81,341)				(117,726)				(81,341)	(117,726)
Retained deficit		(852,458)				(1,074,617)				(852,458)	(1,074,617)
Total shareholders' equity		1,036,903				744,538				1,036,903	744,538
Total liabilities and shareholders' equity		2,348,037				2,076,715				2,348,037	2,076,715
Parenthetical information [Abstract]
Fixed maturities, amortized cost		482,629				548,528				482,629	548,528
Common stock, par value (in dollars per share)		$ 1				$ 1				$ 1	$ 1
Common stock, shares authorized (in shares)		1,000,000				1,000,000				1,000,000	1,000,000
Common stock, shares issued (in shares)		340,047				340,047				340,047	340,047
Common stock, shares outstanding (in shares)		338,560				337,758				338,560	337,758
Treasury stock, shares at cost (in shares)		1,487				2,289				1,487	2,289
Revenues:
Investment income, net of expenses										6,985	5,033	6,921
Realized investment gains, net										395	830	9,895
Other income										0	0	17,775
Total revenues										7,380	5,863	34,591
Expenses:
Operating expenses										1,383	511	2,227
Interest expense										69,648	79,663	99,344
Total expenses										71,031	80,174	101,571
Income (loss) before tax										(63,651)	(74,311)	(66,980)
Benefit from income taxes										0	0	0
Equity in undistributed net income (loss) of subsidiaries										315,600	24,463	(860,099)
Net income (loss)										251,949	(49,848)	(927,079)
Other comprehensive income (loss), net of tax										36,385	(69,563)	(78,287)
Comprehensive income (loss)										288,334	(119,411)	(1,005,366)
Cash flows from operating activities:
Net income (loss)										251,949	(49,848)	(927,079)
Adjustments to reconcile net loss to net cash used in operating activities:
Equity in undistributed net (income) loss of subsidiaries										(315,600)	(24,463)	860,099
Other										14,862	21,693	23,765
Change in certain assets and liabilities:
Accounts receivable - affiliates										68	289	(753)
Income taxes receivable										480	(3)	5,909
Accrued investment income										194	(2,611)	2,702
Accrued interest										(188)	(15,577)	17,288
Net cash used in operating activities										(48,235)	(70,520)	(18,069)
Cash flows from investing activities:
Transactions with subsidiaries										0	(800,000)	(100,000)
Purchase of fixed maturities										(553,538)	(563,968)	(120,181)
Sale of fixed maturities										613,322	148,608	409,601
Net cash (used in) provided by investing activities										59,784	(1,215,360)	189,420
Cash flows from financing activities:
Repayment of long-term debt										(21,767)	(17,235)	(53,107)
Net proceeds from convertible senior notes										0	484,625	0
Common stock shares issued										0	663,335	0
Net cash provided by (used in) financing activities										(21,767)	1,130,725	(53,107)
Net (decrease) increase in cash and cash equivalents										(10,218)	(155,155)	118,244
Cash and cash equivalents at beginning of year					20,725				175,880	20,725	175,880	57,636
Cash and cash equivalents at end of year		$ 10,507				$ 20,725				$ 10,507	$ 20,725	$ 175,880
Dividends and Dividend Restrictions [Abstract]
Percentage of statutory policyholders' surplus used to determine maximum allowable dividends (in hundredths)		10.00%								10.00%