Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Withdrawal Utilization [Member] Level 3 [Member]	Mar. 31, 2013 Withdrawal Utilization [Member] Level 3 [Member] Maximum [Member]	Mar. 31, 2013 Withdrawal Utilization [Member] Level 3 [Member] Minimum [Member]	Mar. 31, 2013 Withdrawal Rates [Member] Level 3 [Member]	Mar. 31, 2013 Withdrawal Rates [Member] Level 3 [Member] Maximum [Member]	Mar. 31, 2013 Withdrawal Rates [Member] Level 3 [Member] Minimum [Member]	Mar. 31, 2013 Lapse Rates [Member] Level 3 [Member]	Mar. 31, 2013 Lapse Rates [Member] Level 3 [Member] Maximum [Member]	Mar. 31, 2013 Lapse Rates [Member] Level 3 [Member] Minimum [Member]	Mar. 31, 2013 Reset Elections [Member] Level 3 [Member]	Mar. 31, 2013 Reset Elections [Member] Level 3 [Member] Maximum [Member]	Mar. 31, 2013 Reset Elections [Member] Level 3 [Member] Minimum [Member]	Mar. 31, 2013 Equity Volatility [Member] Level 3 [Member]	Mar. 31, 2013 Equity Volatility [Member] Level 3 [Member] Maximum [Member]	Mar. 31, 2013 Equity Volatility [Member] Level 3 [Member] Minimum [Member]	Mar. 31, 2013 Policyholder Behavior Assumptions [Member]	Mar. 31, 2012 Policyholder Behavior Assumptions [Member]	Mar. 31, 2013 Monthly N.A.V Calulation [Member] Alternative Assets [Member] Limited Partnerships and Other Alternative Investments [Member] Level 3 [Member]	Dec. 31, 2012 Monthly N.A.V Calulation [Member] Alternative Assets [Member] Limited Partnerships and Other Alternative Investments [Member] Level 3 [Member]
Fair value Measurement Significant Unobservable Input [Line Items]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value Based on Inputs																		$ 337	$ 314
Fair Value Inputs [Abstract]
Range of Values-Unobservable Inputs		100.00%	20.00%		8.00%	0.00%		75.00%	0.00%		75.00%	20.00%		50.00%	10.00%
Positive or negative relationship of change in input to change in fair value measurement	Increase			Increase			Decrease			Increase			Increase
Derivative, Gain (Loss) on Derivative, Net																$ 1	$ 0