Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 74,828	$ 70,890
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	475,000,000	475,000,000
Common stock, shares issued (in shares)	125,244,634	124,626,786
Common stock, shares outstanding (in shares)	83,770,697	85,342,156
Treasury stock, shares (in shares)	41,473,937	39,284,630