Schedule II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Valuation and Qualifying Accounts
Balance at Beginning of Period	$ 1,971	$ 1,027	$ 576
Charged to Costs and Expenses	530	4,285	603
Deductions	(867)	(3,341)	(152)
Balance at End of Period	1,634	1,971	1,027
Accrued warranty reserves
Valuation and Qualifying Accounts
Balance at Beginning of Period	8,050	6,487	3,794
Charged to Costs and Expenses	2,445	8,972	4,427
Deductions	(4,689)	(7,409)	(1,734)
Balance at End of Period	5,806	8,050	6,487
Valuation allowance for deferred tax assets
Valuation and Qualifying Accounts
Balance at Beginning of Period	69,646	47,748	2,848
Charged to Costs and Expenses	17,415	21,898	44,900
Deductions	(548)
Balance at End of Period	86,513	69,646	47,748
Reserve for Inventory
Valuation and Qualifying Accounts
Balance at Beginning of Period	1,798	1,186	1,118
Charged to Costs and Expenses	1,177	266	214
Deductions	(1,994)	346	(146)
Balance at End of Period	$ 981	$ 1,798	$ 1,186