Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Common Class A
Common stock, par value (in dollars per share)	$ 0.000004	$ 0.000004
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares, issued (in shares)	42,225,817	30,820,502
Common stock, shares, outstanding (in shares)	42,225,817	30,820,502
Common Class B
Common stock, par value (in dollars per share)	$ 0.000004	$ 0.000004
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares, issued (in shares)	4,110,108	9,777,757
Common stock, shares, outstanding (in shares)	4,110,108	9,777,757