Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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Name:	us-gaap_SeveranceCosts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Separation Benefits - Additional Information (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2019 USD ($) Store	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost And Reserve [Line Items]
Number of remaining operated sites \| Store			46
Separate benefit costs	$ 0.4
Litigation settlement, amount awarded to plaintiff					$ 1.7
General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge			$ 0.1	$ 0.8	$ 1.7
Spinoff [Member] \| General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Severance and benefit costs		$ 5.4