Schedule of Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Common Stock, Shares, Outstanding beginning of period			89,114,265
Issuance of shares pursuant to equity-based plans			$ 0	$ 1
Adjustments Related to Tax Withholding for Share-based Compensation			1	1
Stockholders' Equity			2,416	2,344
Dividends declared			(62)	(59)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 46	$ 32	110	105
Net Income			$ 110	105
Common Stock, Shares, Outstanding end of period	89,238,206		89,238,206
Stockholders' Equity	$ 2,465	$ 2,392	$ 2,465	$ 2,392
Common Stock [Member]
Common Stock, Shares, Outstanding beginning of period			89,114,265	88,946,704
Issuances of shares pursuant to equity-based plans			123,941	115,856
Common Stock, Shares, Outstanding end of period	89,238,206	89,062,560	89,238,206	89,062,560
Common Stock Including Additional Paid in Capital [Member]
Issuance of shares pursuant to equity-based plans			$ 0	$ 1
Adjustments Related to Tax Withholding for Share-based Compensation			(1)	(1)
Stockholders' Equity			1,207	1,201
Dividends declared			0	0
Stockholders' Equity	$ 1,208	$ 1,203	1,208	1,203
AOCI Attributable to Parent [Member]
Stockholders' Equity			(8)	(7)
Stock-based compensation			0	0
Dividends declared			0	0
Stockholders' Equity	(8)	(7)	(8)	(7)
Retained Earnings [Member]
Stockholders' Equity			1,217	1,150
Stock-based compensation			0	0
Dividends declared			(62)	(59)
Net Income				105
Stockholders' Equity	$ 1,265	$ 1,196	$ 1,265	$ 1,196