Income Taxes (Current and deferred components of the Company's income tax (expense) benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current tax (expense) benefit	$ (142)	$ (220)	$ (318)
Deferred income tax (expense) benefit	(136)	150	(1)
Income tax (expense) benefit	$ (278)	$ (70)	$ (319)