Inventories - Valuation Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Inventory valuation allowance, beginning of the year	$ 5,317	$ 2,701
Inventory scrapped	(1,636)	(151)
Inventory utilized	(954)	(856)
Subtotal—usage	(2,590)	(1,007)
Write-downs of inventory valuation and transfers from other liabilities	7,074	3,623
Inventory valuation allowance, end of the year	$ 9,801	$ 5,317