Schedule of Stockholders Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Common Stock, Shares, Outstanding beginning of period			89,387,124				89,387,124
Issuance of shares pursuant to equity-based plans	$ 0	$ 1	$ 0	$ 0	$ 1	$ 0
Stockholders' Equity	2,646	2,638	2,591	2,542	2,548	2,506	$ 2,591	$ 2,506
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent			1		1	1
Dividends declared	(36)	(35)	(35)	(35)	(35)	(32)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (17)	39	81	55	25	73	$ 103	153
Reclassification of stranded tax effects due to Tax Reform						0
Common Stock, Shares, Outstanding end of period	89,509,783						89,509,783
Stockholders' Equity	$ 2,595	$ 2,646	$ 2,638	$ 2,564	$ 2,542	$ 2,548	$ 2,595	$ 2,564
Common Stock, Dividends, Per Share, Declared	$ 0.4075	$ 0.3850	$ 0.3850	$ 0.3850	$ 0.3850	$ 0.3625
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	$ 2	$ 3		$ 2	$ 2
Common Stock [Member]
Common Stock, Shares, Outstanding beginning of period	89,506,951	89,464,521	89,387,124	89,371,560	89,356,311	89,267,959	89,387,124	89,267,959
Issuances of shares pursuant to equity-based plans	2,832	42,430	77,397	414	15,249	88,352
Common Stock, Shares, Outstanding end of period	89,509,783	89,506,951	89,464,521	89,371,974	89,371,560	89,356,311	89,509,783	89,371,974
Common Stock Including Additional Paid in Capital [Member]
Issuance of shares pursuant to equity-based plans	$ 0	$ 1	$ 0	$ 0	$ 1	$ 0
Stockholders' Equity	1,224	1,220	1,220	1,215	1,212	1,212	$ 1,220	$ 1,212
Dividends declared	0	0	0	0	0	0
Stockholders' Equity	1,226	1,224	1,220	1,217	1,215	1,212	1,226	1,217
Shares Granted, Value, Share-based Payment Arrangement, after Forfeiture	2	3		2	2
AOCI Attributable to Parent [Member]
Stockholders' Equity	(9)	(9)	(10)	(7)	(8)	(7)	(10)	(7)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent			1	0	1	1
Dividends declared	0	0	0	0	0	0
Reclassification of stranded tax effects due to Tax Reform						(2)
Stockholders' Equity	(9)	(9)	(9)	(7)	(7)	(8)	(9)	(7)
Retained Earnings [Member]
Stockholders' Equity	1,431	1,427	1,381	1,334	1,344	1,301	1,381	1,301
Dividends declared	36	35	35	35	35	32
Reclassification of stranded tax effects due to Tax Reform						(2)
Stockholders' Equity	$ 1,378	$ 1,431	$ 1,427	$ 1,354	$ 1,334	$ 1,344	$ 1,378	$ 1,354