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, 2015		Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fixed maturities, available for sale, at fair value	$ 2,693,323		$ 2,800,593
Trading account assets, at fair value	6,068		6,131
Equity securities, available for sale	17		17
Separate account assets	44,111,486		44,101,699
Receivables from parents and affiliates	59,703		60,490
Payables to parent and affiliates	69,218		71,675
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	2,693,323		2,800,593
Trading account assets, at fair value	6,068		6,131
Equity securities, available for sale	17		17
Short-term investments	101,798		57,185
Cash equivalents	225
Other long-term investments	139,839		95,191
Reinsurance recoverable	3,300,612		2,996,154
Subtotal excluding separate account assets	6,282,665		5,996,564
Separate account assets	44,111,486	[1]	44,101,699	[1]
Total assets	50,394,151		50,098,263
Future policy benefits	3,430,249	[2]	3,112,411	[2]
Total liabilities	3,430,249		3,112,411
Receivables from parents and affiliates	40,783		41,068
Payables to parent and affiliates	0		0
DerivativeAssetFairValueGrossLiability	(16,185)	[3]	(21,249)	[3]
DerivativeLiabilityFairValueGrossAsset	(14,108)	[3]	(24,288)	[3]
Fair Value, Measurements, Recurring [Member] | Other Long-term Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
DerivativeLiabilityFairValueGrossAsset	(14,108)	[3]	(24,288)	[3]
Fair Value, Measurements, Recurring [Member] | Payables To Parent And Affiliates [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
DerivativeAssetFairValueGrossLiability	(16,185)	[3]	(21,249)	[3]
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	6,398		6,336
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	22,115		70,789
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	37,481		37,355
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	2,059,086		2,101,684
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	152,772		149,011
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	288,823		302,185
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	126,648		133,233
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	6,068		6,131
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	6,068		6,131
Equity securities, available for sale	0		0
Short-term investments	101,798		57,185
Cash equivalents	0
Other long-term investments	0		0
Reinsurance recoverable	0		0
Subtotal excluding separate account assets	107,866		63,316
Separate account assets	0	[1]	0	[1]
Total assets	107,866		63,316
Future policy benefits	0	[2]	0	[2]
Total liabilities	0		0
Receivables from parents and affiliates	0		0
Payables to parent and affiliates	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
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	6,068		6,131
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	2,526,163		2,643,999
Trading account assets, at fair value	0		0
Equity securities, available for sale	17		17
Short-term investments	0		0
Cash equivalents	0
Other long-term investments	153,312		118,846
Reinsurance recoverable	0		0
Subtotal excluding separate account assets	2,696,260		2,781,610
Separate account assets	44,111,486	[1]	44,101,699	[1]
Total assets	46,807,746		46,883,309
Future policy benefits	0	[2]	0	[2]
Total liabilities	16,185		21,249
Receivables from parents and affiliates	16,768		18,748
Payables to parent and affiliates	16,185		21,249
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	6,398		6,336
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	22,115		70,789
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	37,481		37,355
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	1,940,764		1,985,614
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	103,934		108,487
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	288,823		302,185
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	126,648		133,233
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]
Cash equivalents	225		225
Other long-term investments	635		633
Reinsurance recoverable	3,300,612		2,996,154
Total assets	3,492,647		3,175,926
Future policy benefits	3,430,249		3,112,411
Total liabilities	3,430,249		3,112,411
Receivables from parents and affiliates	24,015		22,320
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	167,160		156,594
Trading account assets, at fair value	0		0
Equity securities, available for sale	0		0
Short-term investments	0		0
Cash equivalents	225
Other long-term investments	635		633
Reinsurance recoverable	3,300,612		2,996,154
Subtotal excluding separate account assets	3,492,647		3,175,926
Separate account assets	0	[1]	0	[1]
Total assets	3,492,647		3,175,926
Future policy benefits	3,430,249	[2]	3,112,411	[2]
Total liabilities	3,430,249		3,112,411
Receivables from parents and affiliates	24,015		22,320
Payables to parent and affiliates	0		0
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	118,322		116,070
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	48,838		40,524
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	$ 0		$ 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] As of March 31, 2015, the net embedded derivative liability position of $3,430 million includes $41 million of embedded derivatives in an asset position and $3,471 million of embedded derivatives in a liability position. As of December 31, 2014, the net embedded derivative liability position of $3,112 million includes $55 million of embedded derivatives in an asset position and $3,167 million of embedded derivatives in a liability position.

[3] “Netting” amounts represent cash collateral of ($2.1) million and $3.0 million as of March 31, 2015 and December 31, 2014, respectively, and the impact of offsetting asset and liability positions held with the same counterparty, subject to master netting arrangements.