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	Jun. 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	$ 4,778,391		$ 5,273,767
Trading account assets, at fair value	7,621		38,578
Equity securities, available for sale	3,205		3,071
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	4,778,391		5,273,767
Trading account assets, at fair value	7,621		38,578
Equity securities, available for sale	3,205		3,071
Short-term investments	99,656		237,601
Cash equivalents	3,148		8,112
Other long-term investments	178,715		152,345
Reinsurance recoverable	1,761,274		1,747,757
Other assets	24,794		25,225
Subtotal excluding separate account assets	6,856,804		7,486,456
Separate account assets	43,645,528		42,942,758	[1]
Total assets	50,502,332		50,429,214
Future policy benefits	1,795,715		1,783,595
Other liabilities	0		0
Total liabilities	1,795,715		1,783,595
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	45,739		86,035
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	45,739		86,035
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	101,000		100,075
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	101,000		100,075
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	113,831		134,810
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	113,831		134,810
Corporate Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	3,517,142		3,887,713
Corporate 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	3,517,142		3,887,713
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	187,990	[2]	177,384	[2]
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	187,990		177,384
Trading account assets, at fair value	2,036		31,571
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	445,795		491,757
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	445,795		491,757
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	366,894	[3]	395,993	[3]
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	366,894		395,993
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	5,585		7,007
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	7,110		6,705
Trading account assets, at fair value	5,388		6,804
Equity securities, available for sale	0		3,071
Short-term investments	97,649		227,235
Cash equivalents	3,148		8,112
Other long-term investments	0		0
Reinsurance recoverable	0		0
Other assets	0		0
Subtotal excluding separate account assets	113,295		251,927
Separate account assets	1,129,128		1,039,821	[1]
Total assets	1,242,423		1,291,748
Future policy benefits	0		0
Other liabilities	0		0
Total liabilities	0		0
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
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
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
Fair Value, Inputs, Level 1 [Member] | Corporate 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	7,110		6,705
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
Trading account assets, at fair value	0		0
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
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
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	5,388		6,804
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	4,627,054		5,128,841
Trading account assets, at fair value	2,036		31,571
Equity securities, available for sale	3,205		0
Short-term investments	2,007		10,366
Cash equivalents	0		0
Other long-term investments	215,589		191,144
Reinsurance recoverable	0		0
Other assets	24,794		25,225
Subtotal excluding separate account assets	4,874,685		5,387,147
Separate account assets	42,516,400		41,902,937	[1]
Total assets	47,391,085		47,290,084
Future policy benefits	0		0
Other liabilities	37,179		40,012
Total liabilities	37,179		40,012
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	45,739		86,035
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	101,000		100,075
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	113,831		134,810
Fair Value, Inputs, Level 2 [Member] | Corporate 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	3,417,571		3,791,350
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	136,224		128,821
Trading account assets, at fair value	2,036		31,571
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	445,795		491,757
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	366,894		395,993
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
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other long-term investments	305
Reinsurance recoverable	1,761,274
Total assets	1,906,003
Future policy benefits	1,795,715
Total liabilities	1,795,715
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	144,227		138,221
Trading account assets, at fair value	197		203
Equity securities, available for sale	0		0
Short-term investments	0		0
Cash equivalents	0		0
Other long-term investments	305		1,213
Reinsurance recoverable	1,761,274		1,747,757
Other assets	0		0
Subtotal excluding separate account assets	1,906,003		1,887,394
Separate account assets	0		0	[1]
Total assets	1,906,003		1,887,394
Future policy benefits	1,795,715		1,783,595
Other liabilities	0		0
Total liabilities	1,795,715		1,783,595
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
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
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
Fair Value, Inputs, Level 3 [Member] | Corporate 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	92,461		89,658
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	51,766		48,563
Trading account assets, at fair value	0		0
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
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
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	197		203
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
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	[4]
Trading account assets, at fair value	0		0	[4]
Equity securities, available for sale	0		0	[4]
Short-term investments	0		0	[4]
Cash equivalents	0		0	[4]
Other long-term investments	(37,179)		(40,012)	[4]
Reinsurance recoverable	0		0	[4]
Other assets	0		0	[4]
Subtotal excluding separate account assets	(37,179)		(40,012)	[4]
Separate account assets	0		0	[1],[4]
Total assets	(37,179)		(40,012)	[4]
Future policy benefits	0		0	[4]
Other liabilities	(37,179)		(40,012)	[4]
Total liabilities	(37,179)		(40,012)	[4]
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
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	[4]
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
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	[4]
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
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	[4]
Netting And Collateral [Member] | Corporate Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	0
Netting And Collateral [Member] | Corporate 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	[4]
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
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	[4]
Trading account assets, at fair value	0		0	[4]
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
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	[4]
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
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	[4]
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		$ 0	[4]

[1] 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.

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

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

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