Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts receivable, allowances	$ 284	$ 285
Property and equipment, accumulated depreciation	$ 10,227	$ 8,968
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	495,000,000	15,041,000
Common stock, shares issued	20,336,000	4,382,000
Common stock, shares outstanding	20,336,000	4,382,000
Series 1
Redeemable convertible preferred stock, shares authorized	0	5,334,000
Redeemable convertible preferred stock, shares issued	0	5,334,000
Redeemable convertible preferred stock, shares outstanding	0	5,334,000
Series 2
Redeemable convertible preferred stock, shares authorized	0	2,979,000
Redeemable convertible preferred stock, shares issued	0	2,552,000
Redeemable convertible preferred stock, shares outstanding	0	2,552,000