Consolidated Balance Sheet (Parenthetical) (Unaudited) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Trade, allowance for doubtful accounts	$ 5	$ 5
Deferred debt issuance costs	$ 21	$ 21
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	450,000,000	450,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, outstanding	148,074,536	150,068,040
Treasury stock, shares	2,412,087	23,963