CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
CONSOLIDATED BALANCE SHEETS
Common stock voting, par value (in dollars per share)	$ 0.0025	$ 0.0025
Common stock voting, shares authorized (in shares)	900,000,000	900,000,000
Common stock voting, shares issued (in shares)	263,370,594	262,937,139
Common stock voting, shares outstanding (in shares)	243,745,023	243,089,514
Treasury stock, shares (in shares)	19,625,571	19,847,625