Commitments and Contingencies (PurOb) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)
Number of previous claims experienced | item	0
Future minimum unconditional purchase obligations
Net sales and use taxes	$ 6,978
Sales and use tax liability	11,348	$ 10,108
Sales and excise tax receivable	4,370	$ 3,879
Prepaid expense and other current assets
Future minimum unconditional purchase obligations
Sales and excise tax receivable	4,370
Accrued Expenses and Other Liabilities
Future minimum unconditional purchase obligations
Sales and use tax liability	$ 11,348