Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		$ 3,129,951	$ 2,712,238
Policy loans		1,468,796	1,284,284
Funds withheld at interest		5,880,203	5,922,561
Cash and cash equivalents		1,525,275	1,645,669		$ 923,647	$ 1,259,892
Short-term investments		558,284	97,694
Other invested assets		1,298,120	1,198,319
Accrued investment income		339,452	261,096
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities		13,663,873	12,591,497
Collateral finance and securitization notes		899,161	773,979
Carrying Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		3,129,951	2,712,238
Policy loans		1,468,796	1,284,284
Funds withheld at interest	[1]	5,956,380	5,897,202
Cash and cash equivalents	[2]	1,118,754	745,823
Short-term investments	[2]	27,511	52,504
Other invested assets	[2]	399,799	465,720
Accrued investment income		339,452	261,096
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	9,746,870	9,623,596
Long And Short Term Debt		2,297,548	2,297,704
Collateral finance and securitization notes		899,161	773,979	[3]
Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		3,197,808	2,803,942
Policy loans		1,468,796	1,284,284
Funds withheld at interest	[1]	6,311,780	6,367,165
Cash and cash equivalents	[2]	1,118,754	745,823
Short-term investments	[2]	27,511	52,504
Other invested assets	[2]	444,342	518,261
Accrued investment income		339,452	261,096
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	9,841,576	9,666,240
Long And Short Term Debt		2,415,119	2,501,810
Collateral finance and securitization notes		791,275	666,262	[3]
Estimate of Fair Value Measurement [Member] | Net Asset Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		0	0
Policy loans		0	0
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	293,599	248,722
Accrued investment income		0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	0	0
Long And Short Term Debt		0	0
Collateral finance and securitization notes		0	0	[3]
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		0	0
Policy loans		0	0
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	1,118,754	745,823
Short-term investments	[2]	27,511	52,504
Other invested assets	[2]	4,445	4,674
Accrued investment income		0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	0	0
Long And Short Term Debt		0	0
Collateral finance and securitization notes		0	0	[3]
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		0	0
Policy loans		1,468,796	1,284,284
Funds withheld at interest	[1]	0	0
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	34,886	35,446
Accrued investment income		339,452	261,096
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	0	0
Long And Short Term Debt		0	0
Collateral finance and securitization notes		0	0	[3]
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage loans on real estate		3,197,808	2,803,942
Policy loans		0	0
Funds withheld at interest	[1]	6,311,780	6,367,165
Cash and cash equivalents	[2]	0	0
Short-term investments	[2]	0	0
Other invested assets	[2]	111,412	229,419
Accrued investment income		0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Interest-sensitive contract liabilities	[1]	9,841,576	9,666,240
Long And Short Term Debt		2,415,119	2,501,810
Collateral finance and securitization notes		$ 791,275	$ 666,262	[3]

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

[3] Prior period balances have been updated to conform with current period presentation for the adoption of the accounting standard update "Simplifying the Presentation of Debt Issuance Costs."