CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2017	Dec. 31, 2016
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)	264,135,545	264,130,544
Common stock voting, shares outstanding (in shares)	242,110,745	243,785,485
Treasury stock, shares (in shares)	22,024,800	20,345,059