Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,276	$ 4,183
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	30,000,000	30,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	187,500,000	187,500,000
Common stock, shares issued (in shares)	125,397,214	124,794,986
Common stock, shares outstanding (in shares)	121,186,960	120,584,732
Treasury stock, shares (in shares)	4,210,254	4,210,254