CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 15,317	$ 14,850
Preferred stock, issued	0	0
Common stock, shares issued	91,294,136	94,080,840
Common stock, shares outstanding	91,294,136	94,080,840
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01