CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED BALANCE SHEETS
Allowance for doubtful accounts receivable, current (in dollars)	$ 15,867	$ 17,495
Intangible assets, accumulated amortization (in dollars)	$ 322,611	$ 294,449
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)	266,072,787	265,822,402
Common stock voting, shares outstanding (in shares)	214,502,639	225,272,174
Treasury stock, shares (in shares)	51,570,148	40,550,228