CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
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)	261,904,809	261,420,126
Common stock voting, shares outstanding (in shares)	242,055,377	241,449,423
Treasury stock, shares (in shares)	19,849,432	19,970,703