CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Class A common stock
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	65,855,000	61,292,000
Common stock, shares outstanding	65,855,000	61,292,000
Class B common stock
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	12,199,000	13,091,000
Common stock, shares outstanding	12,199,000	13,091,000