Commitments and Contingencies - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) store Facility	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Other Commitments [Line Items]
Number of owned stores that have leases | Facility	23
Expense related to ground leases | $	$ 8,229	$ 6,898	$ 4,578
Commitment to acquire stores
Other Commitments [Line Items]
Number of properties to be acquired	18
Other commitment | $	$ 271,526
Commitment to acquire stores, 2019
Other Commitments [Line Items]
Other commitment | $	$ 247,498
Number of store acquisitions expected to close	16
Commitment to acquire stores, 2020
Other Commitments [Line Items]
Other commitment | $	$ 24,028
Number of store acquisitions expected to close	2
Commitment to acquire stores with joint venture partners
Other Commitments [Line Items]
Number of properties to be acquired	13
Other commitment | $	$ 73,860
Commitment to acquire stores with joint venture partners, 2019
Other Commitments [Line Items]
Number of store acquisitions expected to close	11
Commitment to acquire stores with joint venture partners, 2020
Other Commitments [Line Items]
Number of store acquisitions expected to close	2