CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowances, accounts receivable	$ 564	$ 2,138
Warranty obligations, current at fair value	6,794	4,288
Warranty obligations, non-current at fair value	$ 13,012	$ 7,469
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)	123,109,000	107,035,000
Common stock, shares outstanding (in shares)	123,109,000	107,035,000