CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Receivables, allowances	$ 1,406	$ 814
Accumulated depreciation	505,660	411,418
Total accumulated amortization	$ 184,614	$ 144,946
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	31,261,000	30,960,000
Common stock, shares outstanding (in shares)	31,261,000	30,960,000