CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowances, accounts receivable	$ 374	$ 564
Warranty obligations, current at fair value	6,578	6,794
Warranty obligations, non-current at fair value	$ 13,847	$ 13,012
Common stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	125,072,000	123,109,000
Common stock, shares outstanding (in shares)	125,072,000	123,109,000