CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Issuance costs (less than)	$ 1	$ 1	$ 1
Common Stock, Dividends, Per Share, Cash Paid	$ 4.44	$ 3.93	$ 3.48