Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary Of Significant Accounting Policies [Line Items]
Useful life of property	40 years
Depreciation expense from operation	$ 36.7	$ 29.8	$ 22.1
Real estate cost capitalized excluding interest cost	8.5	6.7	6.1
Real estate interest cost capitalized incurred	4.1	2.2	2.6
Accretion of below-market leases	0	0	1.0
Annual amortization estimated for 2014	2.7
Annual amortization estimated for 2015	1.3
Annual amortization estimated for 2016	1.3
Remaining weighted average amortization period	2 years 4 months 24 days
In Place Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of lease cost	2.6	0	0.1
Tenant Relationship [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of lease cost	$ 1.5	$ 0.6	$ 1.2
Minimum [Member] | Land, Buildings and Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property	20 years
Maximum [Member] | Land, Buildings and Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property	40 years
Maximum [Member] | Leasehold Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property	20 years