Related Parties (Narrative) (Details) - Related parties [Member] $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) store property	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Related Parties
Number of stores | store	71
Number of surplus property | property	1
Lease payments under related party operating leases | $	$ 4.7	$ 4.7	$ 4.6