Fair Value of Assets and Liabilities (Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	$ 4,527,910		$ 5,273,767	[1]
Trading account assets, at fair value	7,926		38,578
Equity securities, available for sale	22		3,071	[1]
Separate account assets	45,134,054		42,942,758
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	4,527,910		5,273,767	[2]
Trading account assets, at fair value	7,926		38,578	[2]
Equity securities, available for sale	22		3,071	[2]
Short-term investments	175,729		237,601	[2]
Cash equivalents	39		8,112	[2]
Other long-term investments	165,305		152,345	[2]
Reinsurance recoverable	1,822,323		1,747,757	[2]
Other assets	24,696		25,225	[2]
Subtotal excluding separate account assets	6,723,950		7,486,456	[2]
Separate account assets	45,134,054	[3]	42,942,758	[2],[3]
Total assets	51,858,004		50,429,214	[2]
Future policy benefits	1,886,648		1,783,595	[2]
Other liabilities	0		0	[2]
Total liabilities	1,886,648		1,783,595	[2]
US Treasury And Government [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	35,764		86,035	[1]
US Treasury And Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	35,764		86,036	[2]
Obligations of U.S. states and their political subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	102,915		94,158	[1]
Obligations of U.S. states and their political subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	102,915		94,158	[2]
Foreign Government Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	56,325		77,231	[1]
Foreign Government Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	56,325		77,230	[2]
Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	3,377,235		3,951,209	[1]
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	3,377,235		3,951,209	[2]
Asset-backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	184,985	[4]	177,384	[1],[4]
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	184,985		177,384	[2]
Trading account assets, at fair value	2,029		31,571	[2]
Commercial Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	429,529		491,757	[1]
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	429,529		491,757	[2]
Residential Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	341,157	[5]	395,993	[1],[5]
Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	341,157		395,993	[2]
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets, at fair value	5,897		7,007	[2]
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		6,705	[2]
Trading account assets, at fair value	5,702		6,804	[2]
Equity securities, available for sale	0		3,071	[2]
Short-term investments	175,729		227,235	[2]
Cash equivalents	39		8,112	[2]
Other long-term investments	0		0	[2]
Reinsurance recoverable	0		0	[2]
Other assets	0		0	[2]
Subtotal excluding separate account assets	181,470		251,927	[2]
Separate account assets	171,842	[3]	1,039,821	[2],[3]
Total assets	353,312		1,291,748	[2]
Future policy benefits	0		0	[2]
Other liabilities	0		0	[2]
Total liabilities	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | US Treasury And Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Obligations of U.S. states and their political subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Foreign Government Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		6,705	[2]
Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Trading account assets, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets, at fair value	5,702		6,804	[2]
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	4,374,817		5,128,841	[2]
Trading account assets, at fair value	2,029		31,571	[2]
Equity securities, available for sale	22		0	[2]
Short-term investments	0		10,366	[2]
Cash equivalents	0		0	[2]
Other long-term investments	195,750		191,144	[2]
Reinsurance recoverable	0		0	[2]
Other assets	24,696		25,225	[2]
Subtotal excluding separate account assets	4,597,314		5,387,147	[2]
Separate account assets	44,962,212	[3]	41,902,937	[2],[3]
Total assets	49,559,526		47,290,084	[2]
Future policy benefits	0		0	[2]
Other liabilities	32,202		40,012	[2]
Total liabilities	32,202		40,012	[2]
Fair Value, Inputs, Level 2 [Member] | US Treasury And Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	35,764		86,036	[2]
Fair Value, Inputs, Level 2 [Member] | Obligations of U.S. states and their political subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	102,915		94,158	[2]
Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	56,325		77,230	[2]
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	3,281,845		3,854,846	[2]
Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	127,282		128,821	[2]
Trading account assets, at fair value	2,029		31,571	[2]
Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	429,529		491,757	[2]
Fair Value, Inputs, Level 2 [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	341,157		395,993	[2]
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other long-term investments	1,757
Reinsurance recoverable	1,822,323
Total assets	1,977,368
Future policy benefits	1,886,648
Total liabilities	1,886,648
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	153,093		138,221	[2]
Trading account assets, at fair value	195		203	[2]
Equity securities, available for sale	0		0	[2]
Short-term investments	0		0	[2]
Cash equivalents	0		0	[2]
Other long-term investments	1,757		1,213	[2]
Reinsurance recoverable	1,822,323		1,747,757	[2]
Other assets	0		0	[2]
Subtotal excluding separate account assets	1,977,368		1,887,394	[2]
Separate account assets	0	[3]	0	[2],[3]
Total assets	1,977,368		1,887,394	[2]
Future policy benefits	1,886,648		1,783,595	[2]
Other liabilities	0		0	[2]
Total liabilities	1,886,648		1,783,595	[2]
Fair Value, Inputs, Level 3 [Member] | US Treasury And Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Obligations of U.S. states and their political subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Foreign Government Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	95,390		89,658	[2]
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	57,703		48,563	[2]
Trading account assets, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0		0	[2]
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets, at fair value	195		203	[2]
Netting And Collateral [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Trading account assets, at fair value	0	[6]	0	[2],[6]
Equity securities, available for sale	0	[6]	0	[2],[6]
Short-term investments	0	[6]	0	[2],[6]
Cash equivalents	0	[6]	0	[2],[6]
Other long-term investments	(32,202)	[6]	(40,012)	[2],[6]
Reinsurance recoverable	0	[6]	0	[2],[6]
Other assets	0	[6]	0	[2],[6]
Subtotal excluding separate account assets	(32,202)	[6]	(40,012)	[2],[6]
Separate account assets	0	[3],[6]	0	[2],[3]
Total assets	(32,202)	[6]	(40,012)	[2],[6]
Future policy benefits	0	[6]	0	[2],[6]
Other liabilities	(32,202)	[6]	(40,012)	[2],[6]
Total liabilities	(32,202)	[6]	(40,012)	[2],[6]
Netting And Collateral [Member] | US Treasury And Government [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | US Treasury And Government [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Obligations of U.S. states and their political subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Obligations of U.S. states and their political subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Foreign Government Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Foreign Government Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Asset-backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Trading account assets, at fair value	0	[6]	0	[2],[6]
Netting And Collateral [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Residential Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0	[6]
Netting And Collateral [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value			0	[2],[6]
Netting And Collateral [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets, at fair value	$ 0	[6]	$ 0	[2],[6]

[1] Prior period’s amounts are presented on a basis consistent with the current period presentation.

[2] Includes reclassifications to conform to current period presentation.

[3] Separate account assets represent segregated funds that are invested for certain customers. Investment risks associated with market value changes are borne by the customers, except to the extent of minimum guarantees made by the Company with respect to certain accounts. Separate account liabilities are not included in the above table as they are reported at contract value and not fair value in the Company’s Unaudited Interim Statements of Financial Position.

[4] Includes credit tranched securities collateralized by sub-prime mortgages, credit cards, education loans, and other asset types.

[5] Includes publicly-traded agency pass-through securities and collateralized mortgage obligations.

[6] “Netting” amounts represent the impact of offsetting asset and liability positions held with the same counterparty.