Equity Schedule of Equity by Type (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock	$ 843	$ 22
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	8	0
Proceeds from Issuance of Common Stock	$ 0