Operating Leases - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) Store	Dec. 31, 2018 USD ($)
Operating Leases [Line Items]
Non-cancelable operating leases obligation expiration period	2033
Weighted average remaining lease term	6 years 2 months 12 days
Number of retail sites leased to third party | Store	400
Variable lease payments	$ 0.4
Short-term lease payments	0.1
Operating lease payments	$ 7.0
Weighted average discount rate	6.90%
Sublease rental income	$ 9.5
Lessor operating lease term of expiration	through 2033
Deferred rent income under lease agreement	$ 6.6	$ 6.3
Minimum
Operating Leases [Line Items]
Sublease contract term	1 year
Maximum
Operating Leases [Line Items]
Sublease contract term	10 years