Commitments and Contingencies (Details) - Helium Supply Arrangement [Member] $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Long-term Purchase Commitment [Line Items]
Term of Long Term Supply Arrangement	20 years
Maximum Annual Payment In Event Of Shortfall	$ 8.0
Maximum Payment In Event Of Shortfall	$ 46.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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