Subsequent Events (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended				6 Months Ended
	Aug. 09, 2018 USD ($) store $ / shares shares	Jun. 30, 2018 USD ($) store shares	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($) store shares	Jun. 30, 2017 USD ($)
Subsequent Event [Line Items]
Number of stores acquired | store		15				15
Purchase price to acquire real estate		$ 237,284	$ 70,787	$ 34,641	$ 25,556	$ 308,071	$ 60,197
Subsequent Event [Member]
Subsequent Event [Line Items]
Number of stores acquired | store	3
Purchase price to acquire real estate	$ 47,125
At the Market Equity Distribution Agreement [Member]
Subsequent Event [Line Items]
Shares, issued | shares		0				0
At the Market Equity Distribution Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Shares, issued | shares	343,251
Average price per share | $ / shares	$ 99.75
Net proceeds	$ 33,897