Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity Common Stock Outstanding Roll Forward (Details)

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Stockholders' Equity Common Stock Outstanding Roll Forward (Details) - shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Class of Stock [Line Items]      
Common shares outstanding at beginning of period 353,906,807 366,395,920 364,935,168
Stock Issued During Period, Shares, New Issues 60,602 69,826 57,218
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures 1,704,917 1,105,361 1,403,534
Stock Repurchased and Retired During Period, Shares (8,020,000) (13,664,300)  
Common shares outstanding at end of period 347,652,326 353,906,807 366,395,920
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 2,639,424