Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 70,890	$ 59,963
Par value (in usd per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	475,000,000	475,000,000
Shares issued (in shares)	124,626,786	123,035,859
Shares outstanding (in shares)	85,342,156	85,845,344
Treasury stock, shares	39,284,630	37,190,515