Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7,738	$ 9,175
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	7,500,000	7,500,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	122,375,955	123,984,527
Common stock, shares outstanding	122,375,955	123,984,527