Summary of Significant Accounting Policies - Summary of Estimated Useful Lives (Detail)	6 Months Ended
	Jun. 30, 2018
Minimum [Member] | Building [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Minimum [Member] | Site Improvement [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Maximum [Member] | Building [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years
Maximum [Member] | Site Improvement [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years