Commitments and Contingencies - Commercial Supply Commitments - Recorded Purchase Commitments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Accrual for non-cancellable purchase commitments
Purchase Commitment Write-down	$ 1,353
Commercial Supply Commitments
Accrual for non-cancellable purchase commitments
Purchase Commitment Write-down	$ 1,300