Derivative Instruments (Change in Fair Value of Derivatives Included in the Consolidated Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	$ 103,794	$ (351,360)	$ 68,828	$ (405,484)
Change in fair value of embedded derivatives	144,404	(414,724)	694,564	(583,112)
Call Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	103,267	(347,038)	72,910	(396,399)
2015 Notes Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	0	(1,141)	0	(4,516)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	647	(2,349)	(2,979)	(3,283)
Interest Rate Caps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	(120)	(832)	(1,103)	(1,286)
Fixed Index Annuities - Embedded Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	41,561	(460,031)	421,193	(864,389)
Other Changes in Difference Between Policy Benefit Reserves Computed Using Derivative Accounting Vs. Long-Duration Contracts Accounting [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	102,843	46,448	273,371	285,793
2015 Notes Embedded Conversion Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	$ 0	$ (1,141)	$ 0	$ (4,516)