CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts	$ 8,231	$ 7,812
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock , par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, issued (in shares)	0	0
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	90,232,839	90,151,131
Treasury stock, shares (in shares)	14,031,568	13,616,592