CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 9,993	$ 10,842
Long-term debt, debt discount and issuance costs	$ 6,651	$ 7,271
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	400,000,000	400,000,000
Common stock, issued	272,885,704	271,028,688
Common stock, outstanding	189,049,158	187,626,366
Treasury stock, shares	83,836,546	83,402,322