Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Document Period End Date	Mar. 31, 2013
Intangible assets and goodwill	$ 12,100,000		$ 12,100,000
Intangible assets	4,300,000		4,300,000
Goodwill	7,800,000		7,800,000
Accumulated amortization of identified intangible assets	1,600,000		1,500,000
Amortization expense for identified intangible assets	159,000	18,365,000
Cash and cash equivalents, restricted cash	4,900,000		4,900,000
Accumulated amortization for deferred financing costs	21,800,000		20,500,000
Fair Value, Inputs, Level 2
Significant Accounting Policies [Line Items]
Mortgage notes payable fair value	2,200,000,000		2,200,000,000
Identified Intangible Assets
Significant Accounting Policies [Line Items]
Amortization expense for identified intangible assets	$ 100,000	$ 100,000