SCHEDULE II - Condensed Balance Sheets - Parent Company Only (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2008 [SeniorNotesDebtMember] [NotesIssuedByPartnerReFinanceALlcMember]	Dec. 31, 2010 [SeniorNotesDebtMember] [NotesIssuedByPartnerReFinanceBLlcMember]	Nov. 30, 2006 [JuniorSubordinatedDebtMember] [NotesIssuedByPartnerReFinanceIiIncMember]	Dec. 31, 2011 [ParentCompanyMember]	Dec. 31, 2010 [ParentCompanyMember]	Dec. 31, 2009 [ParentCompanyMember]	Dec. 31, 2008 [ParentCompanyMember]	Dec. 31, 2011 [ParentCompanyMember] [SeniorNotesDebtMember] [NotesIssuedByPartnerReFinanceALlcMember] [FinancialGuaranteeMember]	Dec. 31, 2011 [ParentCompanyMember] [SeniorNotesDebtMember] [NotesIssuedByPartnerReFinanceBLlcMember] [FinancialGuaranteeMember]	Dec. 31, 2011 [ParentCompanyMember] [JuniorSubordinatedDebtMember] [NotesIssuedByPartnerReFinanceIiIncMember] [FinancialGuaranteeMember]
Assets
Fixed maturities, trading securities, at fair value (amortized cost: 2011, $178,674; 2010, $10,356)	$ 13,941,829,000	$ 12,824,389,000						$ 181,117,000	$ 10,337,000
Short-term investments, trading securities, at fair value (amortized cost: 2011, $8,463; 2010, $nil)	42,571,000	49,397,000						8,467,000	0
Cash and cash equivalents	1,342,257,000	2,111,084,000	738,309,000	838,280,000				51,729,000	329,054,000	3,503,000	178,528,000
Investment in subsidiaries								7,693,969,000	7,576,571,000
Intercompany loans and balances receivable								350,265,000	442,290,000
Other, net	70,044,000	83,113,000						10,066,000	13,069,000
Total assets	22,855,373,000	23,364,371,000						8,295,613,000	8,371,321,000
Liabilities Abstract
Intercompany loans and balances payable								1,815,049,000	1,131,463,000
Accounts payable, accrued expenses and other	208,840,000	244,552,000						13,022,000	32,939,000
Total liabilities	16,387,831,000	16,157,452,000						1,828,071,000	1,164,402,000
Shareholders' Equity
Common shares (par value $1.00, issued: 2011, 84,766,693 shares; 2010, 84,033,089 shares)	84,767,000	84,033,000						84,767,000	84,033,000
Preferred shares (par value $1.00; issued and outstanding: 2011, 35,750,000 shares; 2010, 20,800,000 shares; aggregate liquidation value: 2011, $893,750; 2010, $520,000)	35,750,000	20,800,000						35,750,000	20,800,000
Additional paid-in capital	3,803,796,000	3,419,864,000						3,803,796,000	3,419,864,000
Accumulated other comprehensive (loss) income:
Currency translation adjustment	4,267,000	16,101,000						4,267,000	16,101,000
Other accumulated comprehensive (loss) income, net of tax	(16,911,000)	(12,045,000)						(16,911,000)	(12,045,000)
Retained earnings	4,035,103,000	4,761,178,000						4,035,103,000	4,761,178,000
Common shares held in treasury, at cost (2011, 19,444,365 shares; 2010, 14,046,895 shares)	(1,479,230,000)	(1,083,012,000)						(1,479,230,000)	(1,083,012,000)
Total shareholders' equity	6,467,542,000	7,206,919,000	7,645,727,000					6,467,542,000	7,206,919,000
Total liabilities and shareholders' equity	22,855,373,000	23,364,371,000						8,295,613,000	8,371,321,000
Condensed Financial Statements Parentheticals [Abstract]
Fixed maturities, trading securities, amortized cost	13,394,404,000	12,394,797,000						178,674,000	10,356,000
Common shares, par value	$ 1	$ 1						$ 1.00	$ 1.00
Common shares, shares issued	84,766,693	84,033,089						84,766,693	84,033,089
Preferred shares, par value	$ 1	$ 1						$ 1.00	$ 1.00
Preferred shares, shares issued	35,750,000	20,800,000						35,750,000	20,800,000
Preferred shares, shares outstanding	35,750,000	20,800,000						35,750,000	20,800,000
Aggregate liquidation value	893,750,000	520,000,000						893,750,000	520,000,000
Common shares held in treasury, shares	19,444,365	14,046,895						19,444,365	14,046,895
Parent Company Guarantee Disclosures [Abstract]
Full and unconditional guarantee of obligations of non-consolidated, wholly-owned subsidiaries												$ 250,000,000	$ 500,000,000	$ 63,400,000
Interest rate on obligations guaranteed by the Parent Company					6.875%	5.50%	6.44%					6.875%	5.50%	6.44%