CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 3,191	$ 3,545
Current portion of long-term debt, debt issuance cost		483
Long-term debt, debt issuance cost	$ 1,649	$ 3,350
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	300,000,000	300,000,000
Common stock, issued	191,494,741	190,374,801
Common stock, outstanding	148,118,449	147,167,561
Treasury stock, shares	43,376,292	43,207,240