Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) OperatingSegment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Interest expense and loan cost amortization	$ 61.1	$ 45.3	$ 31.5
Capitalized amount of interest	2.8	2.3	$ 1.0
Accumulated amortization of loan costs	$ 10.3	$ 7.8
Lease, initial term	3 months
Lease termination, notice period	30 days
Annualized return of investment	6.00%
Number of segment | OperatingSegment	1
Building and Building Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Real estate assets, estimated useful life	39 years
Building and Building Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Real estate assets, estimated useful life	15 years