Condensed Consolidated Balance Sheets (parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts and notes receivable, allowances (in dollars)	$ 7,211	$ 6,567
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A common stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	475,000	475,000
Common stock, shares issued	219,550	219,237
Common stock, shares outstanding	219,550	219,237