Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Jan. 25, 2013
Stockholders' Equity Attributable to Parent [Abstract]
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Common Stock, Shares Authorized	2,000,000,000	2,000,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Treasury shares	247,566,270	247,566,270
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 535
Stock Repurchase Program, Authorized Amount			$ 1,000