Store Acquisitions and Dispositions - Schedule of Operating Properties Acquired (Detail) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2018 USD ($) store shares	Jun. 30, 2018 USD ($) store shares	Mar. 31, 2018 USD ($) store shares	Sep. 30, 2017 USD ($) store shares	Jun. 30, 2017 USD ($) store shares	Mar. 31, 2017 USD ($) store shares	Sep. 30, 2018 USD ($) store shares	Sep. 30, 2017 USD ($) store shares
Real Estate [Abstract]
Number of Stores | store	6	17	5	4	3	2	28	9
Total Consideration Paid	$ 74,694	$ 237,284	$ 70,787	$ 31,966	$ 34,641	$ 25,556	$ 382,765	$ 92,163
Cash Paid	71,989	148,650	70,171	29,919	16,608	25,541	290,810	72,068
Loan Assumed	0	87,500	0	0	9,463	0	87,500	9,463
Non- controlling interests	0	0	0	0	1,827	0	0	1,827
Investments in Real Estate Ventures	0	(1,024)	489	0	0	0	(535)	0
Net Liabilities/ (Assets) Assumed	2,705	281	127	47	(67)	15	3,113	(5)
Value of OP Units Issued	$ 0	$ 1,877	$ 0	$ 2,000	$ 6,810	$ 0	$ 1,877	$ 8,810
Number of OP Units Issued (in shares) | shares	0	21,768	0	25,520	272,400	0	21,768	297,920
Real estate assets	$ 74,694	$ 237,284	$ 70,787	$ 31,966	$ 34,641	$ 25,556	$ 382,765	$ 92,163
Number of stores acquired | store							15