Investments (Realized Investment Gains Losses Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ (2,447,694)	$ (9,156)	$ (2,461,936)	$ 4,319
Fixed maturities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	87,081	3,042	84,935	4,904
Equity securities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	0	0	0	0
Commercial mortgage and other loans
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(1,395)	12	(1,401)	87
Derivatives
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(2,533,802)	(12,210)	(2,545,412)	(672)
Other long-term investments
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ 422	$ 0	$ (58)	$ 0