CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts receivable, allowances	$ 3,918	$ 3,350
Common stock, par value (in dollars per share)	$ 0.000005	$ 0.000005
Common stock, authorized (in shares)	900,000,000	900,000,000
Common stock, issued (in shares)	0	0
Common stock, outstanding (in shares)	0	0
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	100,000,000	100,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Class A Common
Common stock, par value (in dollars per share)	$ 0.000005	$ 0.000005
Common stock, authorized (in shares)	750,000,000	750,000,000
Common stock, issued (in shares)	90,218,331	86,679,575
Common stock, outstanding (in shares)	75,598,156	72,059,400
Treasury stock (in shares)	14,620,175	14,620,175
Class B Common
Common stock, par value (in dollars per share)	$ 0.000005	$ 0.000005
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	79,387,495	80,608,685
Common stock, outstanding (in shares)	79,387,495	80,608,685