Stockholders' Equity - Voting Rights (Details)	Dec. 31, 2019 Vote
Equity [Abstract]
Number of votes per share held by holders of common stock	1

Represents the number of voting rights per common share held.

No definition available.

Name:	clne_CommonStockVotingRightsPerShare
Namespace Prefix:	clne_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant