Schedule of Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Common Stock, Shares, Outstanding beginning of period			89,267,959				89,267,959
Issuance of shares pursuant to equity-based plans	$ 0	$ 1	$ 0	$ 0	$ 0	$ 0
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	2	2		1	2	(1)
Stockholders' Equity	2,542	2,548	2,506	2,465	2,449	2,416	$ 2,506	$ 2,416
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		1	1
Dividends declared	(35)	(35)	(32)	(33)	(32)	(30)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 55	25	73	53	46	64	153	163
Reclassification of stranded tax effects due to Tax Reform			0				$ (2)
Common Stock, Shares, Outstanding end of period	89,371,974						89,371,974
Stockholders' Equity	$ 2,564	$ 2,542	$ 2,548	$ 2,486	$ 2,465	$ 2,449	$ 2,564	$ 2,486
Common Stock [Member]
Common Stock, Shares, Outstanding beginning of period	89,371,560	89,356,311	89,267,959	89,238,206	89,214,119	89,114,265	89,267,959	89,114,265
Issuances of shares pursuant to equity-based plans	414	15,249	88,352	6,453	24,087	99,854
Common Stock, Shares, Outstanding end of period	89,371,974	89,371,560	89,356,311	89,244,659	89,238,206	89,214,119	89,371,974	89,244,659
Common Stock Including Additional Paid in Capital [Member]
Issuance of shares pursuant to equity-based plans	$ 0	$ 1	$ 0	$ 0	$ 0	$ 0
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	2	2		1	2	(1)
Stockholders' Equity	1,215	1,212	1,212	1,208	1,206	1,207	$ 1,212	$ 1,207
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0
Dividends declared			0
Stockholders' Equity	1,217	1,215	1,212	1,209	1,208	1,206	1,217	1,209
AOCI Attributable to Parent [Member]
Stockholders' Equity	(7)	(8)	(7)		(8)	(8)	(7)	(8)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		1	1
Dividends declared		0	0
Reclassification of stranded tax effects due to Tax Reform			(2)
Stockholders' Equity	(7)	(7)	(8)	(8)		(8)	(7)	(8)
Retained Earnings [Member]
Stockholders' Equity	1,334	1,344	1,301	1,265	1,251	1,217	1,301	1,217
Stock-based compensation		0
Dividends declared	35	35	32	33	32	30
Reclassification of stranded tax effects due to Tax Reform			(2)
Stockholders' Equity	$ 1,354	$ 1,334	$ 1,344	$ 1,285	$ 1,265	$ 1,251	$ 1,354	$ 1,285