Income Taxes (Current and deferred components of the Company's income tax (expense) benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current tax expense	$ (171)	$ (243)	$ (142)
Deferred tax benefit (expense)	20	(168)	(136)
Income tax expense	$ (151)	$ (411)	$ (278)