Increases Decreases in Net Income as Result of Amortization of In-Place Leases Above Market Leases and Below Market Leases (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	$ (10,485)	$ (9,976)	$ (4,460)
In-place leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	(10,248)	(8,859)	(3,388)
Above Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	(5,739)	(5,684)	(2,874)
Below Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	$ 5,502	$ 4,567	$ 1,802