Inventory (Narrative) (Details) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) compressor	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Inventory Disclosure [Abstract]
Allowance for inventory obsolescence	$ 24		$ 24	$ 19	$ 15	$ 15
Available-for-sale or rental, compressor units \| compressor				7
Available-for-sale or rental, finished goods				$ 1,000
Inventory allowance	$ 408	$ 3,400	$ 3,758	$ 0	$ 273

Amount of valuation reserve for inventory.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant