Schedule of Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Payments of Stock Issuance Costs			$ 12
Proceeds from Issuance of Common Stock			$ 271	$ 0
Common Stock, Shares, Outstanding beginning of period			78,228,339
Stockholders' Equity			$ 1,911
Net Income	$ 35	$ 35	$ 85	$ 93
Common Stock, Shares, Outstanding end of period	88,765,629		88,765,629
Stockholders' Equity	$ 2,221		$ 2,221
Common Stock [Member]
Stock Issued During Period, Shares, New Issues	10,400,000
Common Stock, Shares, Outstanding beginning of period			78,228,339	78,085,559
Issuances of shares pursuant to equity-based plans			137,290	116,682
Common Stock, Shares, Outstanding end of period	88,765,629	78,202,241	88,765,629	78,202,241
Common Stock Including Additional Paid in Capital [Member]
Proceeds from Issuance of Common Stock			$ 271
Issuance of shares pursuant to equity-based plans			1	$ 0
Adjustments Related to Tax Withholding for Share-based Compensation			1
Stockholders' Equity			918	911
Stock-based compensation				3
Dividends declared			0	0
Stockholders' Equity	$ 1,191	$ 914	1,191	914
Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity			(7)	(5)
Stock-based compensation			0	0
Dividends declared			0	0
Stockholders' Equity	(7)	(5)	(7)	(5)
Retained Earnings [Member]
Stockholders' Equity			1,000	913
Stock-based compensation			0	0
Dividends declared			(48)	(44)
Net Income			85	93
Stockholders' Equity	1,037	962	1,037	962
Stockholders' Equity, Total [Member]
Proceeds from Issuance of Common Stock			271
Issuance of shares pursuant to equity-based plans			1	0
Stockholders' Equity			1,911	1,819
Stock-based compensation			1	3
Dividends declared			(48)	(44)
Net Income			85	93
Stockholders' Equity	$ 2,221	$ 1,871	$ 2,221	$ 1,871