Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Assets
Mortgage loans on real estate (net of valuation allowances)	$ 2,526,228		$ 2,486,680
Policy loans	1,296,897		1,244,469
Funds withheld at interest	5,814,231		5,771,467
Cash and cash equivalents	1,127,132		923,647		1,001,841	1,259,892
Short-term investments	118,789		139,395
Other invested assets	1,234,779		1,324,960
Accrued investment income	233,816		267,908
Liabilities
Interest-sensitive contract liabilities	12,809,003		12,947,557
Short-term Debt	50,000		0
Short-term Debt, Fair Value	50,000
Long-term debt	2,214,526		2,214,350
Long-term Debt, Fair Value	2,407,939
Collateral finance facility	484,747		484,752
Fair Value Inputs Level 1 Member
Liabilities
Short-term Debt, Fair Value	0
Long-term Debt, Fair Value	0
Fair Value Inputs Level 2 Member
Liabilities
Short-term Debt, Fair Value	50,000
Long-term Debt, Fair Value	0
Fair Value Inputs Level 3 Member
Liabilities
Short-term Debt, Fair Value	0
Long-term Debt, Fair Value	2,407,939
Carrying Value [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	2,526,228		2,486,680
Policy loans	1,296,897		1,244,469
Funds withheld at interest	5,912,727	[1]	5,948,374	[1]
Cash and cash equivalents	594,175	[2]	552,302	[2]
Short-term investments	33,497	[2]	27,823	[2]
Other invested assets	476,249	[2]	491,545	[2]
Accrued investment income	233,816		267,908
Liabilities
Interest-sensitive contract liabilities	10,065,850	[1]	10,228,120	[1]
Short-term Debt	50,000
Debt, Long-term and Short-term, Combined Amount			2,214,350
Collateral finance facility	484,747		484,752
Estimated Fair Value [Member]
Liabilities
Debt, Long-term and Short-term, Combined Amount			2,333,023
Estimated Fair Value [Member] | Fair Value Inputs Level 1 Member
Liabilities
Debt, Long-term and Short-term, Combined Amount			0
Estimated Fair Value [Member] | Fair Value Inputs Level 2 Member
Liabilities
Debt, Long-term and Short-term, Combined Amount			0
Estimated Fair Value [Member] | Fair Value Inputs Level 3 Member
Liabilities
Debt, Long-term and Short-term, Combined Amount			2,333,023
Estimate of Fair Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	2,576,966		2,489,721
Policy loans	1,296,897		1,244,469
Funds withheld at interest	6,236,412	[1]	6,207,342	[1]
Cash and cash equivalents	594,175	[2]	552,302	[2]
Short-term investments	33,497	[2]	27,823	[2]
Other invested assets	519,548	[2]	534,442	[2]
Accrued investment income	233,816		267,908
Liabilities
Interest-sensitive contract liabilities	9,812,347	[1]	9,989,514	[1]
Collateral finance facility	376,193		374,984
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 1 Member
Assets
Mortgage loans on real estate (net of valuation allowances)	0		0
Policy loans	0		0
Funds withheld at interest	0	[1]	0	[1]
Cash and cash equivalents	594,175	[2]	552,302	[2]
Short-term investments	33,497	[2]	27,823	[2]
Other invested assets	5,108	[2]	5,070	[2]
Accrued investment income	0		0
Liabilities
Interest-sensitive contract liabilities	0	[1]	0	[1]
Collateral finance facility	0		0
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 2 Member
Assets
Mortgage loans on real estate (net of valuation allowances)	0		0
Policy loans	1,296,897		1,244,469
Funds withheld at interest	0	[1]	0	[1]
Cash and cash equivalents	0	[2]	0	[2]
Short-term investments	0	[2]	0	[2]
Other invested assets	36,046	[2]	33,886	[2]
Accrued investment income	233,816		267,908
Liabilities
Interest-sensitive contract liabilities	0	[1]	0	[1]
Collateral finance facility	0		0
Estimate of Fair Value Measurement [Member] | Fair Value Inputs Level 3 Member
Assets
Mortgage loans on real estate (net of valuation allowances)	2,576,966		2,489,721
Policy loans	0		0
Funds withheld at interest	6,236,412	[1]	6,207,342	[1]
Cash and cash equivalents	0	[2]	0	[2]
Short-term investments	0	[2]	0	[2]
Other invested assets	478,394	[2]	495,486	[2]
Accrued investment income	0		0
Liabilities
Interest-sensitive contract liabilities	9,812,347	[1]	9,989,514	[1]
Collateral finance facility	$ 376,193		$ 374,984

[1] Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are embedded derivatives and are measured at fair value on a recurring basis.

[2] Carrying values presented herein differ from those presented in the condensed consolidated balance sheets because certain items within the respective financial statement caption are measured at fair value on a recurring basis.