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	Mar. 31, 2013		Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	$ 3,948,208		$ 4,203,450
Trading account assets, at fair value	8,430		7,916
Equity securities, available for sale	22		22
Separate account assets	45,745,140		44,601,720
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	3,948,208		4,203,450
Trading account assets, at fair value	8,430		7,916
Equity securities, available for sale	22		22
Short-term investments	136,281		103,761
Cash equivalents	160		0
Other long-term investments	89,054		132,051
Reinsurance recoverable	1,191,409		1,732,094
Other assets	22,315		22,627
Subtotal excluding separate account assets	5,395,879		6,201,921
Separate account assets	45,745,140	[1]	44,601,720	[1]
Total assets	51,141,019		50,803,641
Future policy benefits	1,230,323		1,793,137
Other liabilities	0		0
Total liabilities	1,230,323		1,793,137
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	4,654		4,686
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	102,443		102,116
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	39,586		55,529
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	2,983,548		3,191,254
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	183,133		187,477
Trading account assets, at fair value	2,014		2,022
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	400,577		394,902
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	234,267		267,486
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	6,416		5,894
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		0
Trading account assets, at fair value	6,149		5,687
Equity securities, available for sale	0		0
Short-term investments	135,193		103,761
Cash equivalents	160		0
Other long-term investments	0		0
Reinsurance recoverable	0		0
Other assets	0		0
Subtotal excluding separate account assets	141,502		109,448
Separate account assets	127,467	[1]	122,142	[1]
Total assets	268,969		231,590
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 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] | 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	6,149		5,687
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	3,770,786		4,038,597
Trading account assets, at fair value	2,014		2,022
Equity securities, available for sale	22		22
Short-term investments	1,088		0
Cash equivalents	0		0
Other long-term investments	139,623		173,348
Reinsurance recoverable	0		0
Other assets	20,315		20,632
Subtotal excluding separate account assets	3,933,848		4,234,621
Separate account assets	45,617,673	[1]	44,479,578	[1]
Total assets	49,551,521		48,714,199
Future policy benefits	0		0
Other liabilities	51,032		42,351
Total liabilities	51,032		42,351
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	4,654		4,686
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	102,443		102,116
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	39,586		55,529
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	2,887,973		3,095,699
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	110,393		118,179
Trading account assets, at fair value	2,014		2,022
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	391,470		394,902
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	234,267		267,486
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	463		1,054
Reinsurance recoverable	1,191,409		1,732,094
Other assets	2,000		1,995
Total assets	1,371,561		1,900,203
Future policy benefits	1,230,323		1,793,137
Total liabilities	1,230,323		1,793,137
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	177,422		164,853
Trading account assets, at fair value	267		207
Equity securities, available for sale	0		0
Short-term investments	0		0
Cash equivalents	0		0
Other long-term investments	463		1,054
Reinsurance recoverable	1,191,409		1,732,094
Other assets	2,000		1,995
Subtotal excluding separate account assets	1,371,561		1,900,203
Separate account assets	0	[1]	0	[1]
Total assets	1,371,561		1,900,203
Future policy benefits	1,230,323		1,793,137
Other liabilities	0		0
Total liabilities	1,230,323		1,793,137
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 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	95,575		95,555
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	72,740		69,298
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	9,107		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	267		207
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]	0
Trading account assets, at fair value	0	[2]	0
Equity securities, available for sale	0	[2]	0
Short-term investments	0	[2]	0
Cash equivalents	0	[2]	0
Other long-term investments	(51,032)	[2]	(42,351)
Reinsurance recoverable	0	[2]	0
Other assets	0	[2]	0
Subtotal excluding separate account assets	(51,032)	[2]	(42,351)
Separate account assets	0	[1],[2]	0	[1]
Total assets	(51,032)	[2]	(42,351)
Future policy benefits	0	[2]	0
Other liabilities	(51,032)	[2]	(42,351)
Total liabilities	(51,032)	[2]	(42,351)
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]	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	[2]	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	[2]	0
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]	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	[2]	0
Trading account assets, at fair value	0	[2]	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	[2]	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	[2]	0
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	[2]	$ 0

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