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	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013	Dec. 31, 2012
Assets
Mortgage loans on real estate (net of valuation allowances)	$ 2,555,800		$ 2,486,680
Policy loans	1,250,635		1,244,469
Funds withheld at interest	5,940,521		5,771,467
Cash and cash equivalents	1,378,117		923,647		973,619	1,259,892
Short-term investments	45,596		139,395
Other invested assets	1,128,375		1,324,960
Accrued investment income	279,368		267,908
Liabilities
Interest-sensitive contract liabilities	12,686,025		12,947,557
Short-term Debt	110,000		0
Long-term debt	2,214,705		2,214,350
Collateral finance facility	482,092		484,752
Estimate of Fair Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	2,654,439		2,489,721
Policy loans	1,250,635		1,244,469
Funds withheld at interest	6,377,951	[1]	6,207,342	[1]
Cash and cash equivalents	861,319	[2]	552,302	[2]
Short-term investments	23,894	[2]	27,823	[2]
Other invested assets	509,067	[2]	534,442	[2]
Accrued investment income	279,368		267,908
Liabilities
Interest-sensitive contract liabilities	9,818,666	[1]	9,989,514	[1]
Short-term Debt, Fair Value	110,000
Long-term Debt, Fair Value	2,438,495
Debt, Long-term and Short-term, Combined Amount			2,333,023
Collateral finance facility	377,403		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	861,319	[2]	552,302	[2]
Short-term investments	23,894	[2]	27,823	[2]
Other invested assets	5,216	[2]	5,070	[2]
Accrued investment income	0		0
Liabilities
Interest-sensitive contract liabilities	0	[1]	0	[1]
Short-term Debt, Fair Value	0
Long-term Debt, Fair Value	0
Debt, Long-term and Short-term, Combined Amount			0
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	1,250,635		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	38,446	[2]	33,886	[2]
Accrued investment income	279,368		267,908
Liabilities
Interest-sensitive contract liabilities	0	[1]	0	[1]
Short-term Debt, Fair Value	110,000
Long-term Debt, Fair Value	0
Debt, Long-term and Short-term, Combined Amount			0
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)	2,654,439		2,489,721
Policy loans	0		0
Funds withheld at interest	6,377,951	[1]	6,207,342	[1]
Cash and cash equivalents	0	[2]	0	[2]
Short-term investments	0	[2]	0	[2]
Other invested assets	465,405	[2]	495,486	[2]
Accrued investment income	0		0
Liabilities
Interest-sensitive contract liabilities	9,818,666	[1]	9,989,514	[1]
Short-term Debt, Fair Value	0
Long-term Debt, Fair Value	2,438,495
Debt, Long-term and Short-term, Combined Amount			2,333,023
Collateral finance facility	377,403		374,984
Reported Value Measurement [Member]
Assets
Mortgage loans on real estate (net of valuation allowances)	2,555,800		2,486,680
Policy loans	1,250,635		1,244,469
Funds withheld at interest	5,958,657	[1]	5,948,374	[1]
Cash and cash equivalents	861,319	[2]	552,302	[2]
Short-term investments	23,894	[2]	27,823	[2]
Other invested assets	460,905	[2]	491,545	[2]
Accrued investment income	279,368		267,908
Liabilities
Interest-sensitive contract liabilities	9,890,923	[1]	10,228,120	[1]
Short-term Debt	110,000
Long-term debt	2,214,705
Debt, Long-term and Short-term, Combined Amount			2,214,350
Collateral finance facility	$ 482,092		$ 484,752

[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.