CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,252	$ 1,269
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	103,100,000	97,200,000
Common stock, shares outstanding (in shares)	103,100,000	96,700,000
Treasury stock, shares (in shares)	0	500,000