Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts receivable, allowances	$ 27,521	$ 21,897
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,150,000,000	1,150,000,000
Common stock, shares issued	119,897,000	109,770,000
Common stock, shares outstanding	119,897,000	109,770,000
Class A Common Stock
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	93,574,000	77,820,000
Common stock, shares outstanding	93,574,000	77,820,000
Class B Common Stock
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	26,323,000	31,950,000
Common stock, shares outstanding	26,323,000	31,950,000