Financing Activity - Mortgage Loan Activity (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Feb. 28, 2013	Mar. 31, 2013
Mortgage Loan February [Member] | Francis Scott Key Mall [Member]
Mortgage Loan Activity [Line Items]
Property		Francis Scott Key Mall
Amount Financed or Extended		$ 62.6
Stated Interest Rate		LIBOR plus 2.60%
Maturity		March 2018
Mortgage Loan February [Member] | Lycoming Mall [Member]
Mortgage Loan Activity [Line Items]
Property		Lycoming Mall
Amount Financed or Extended		35.5
Stated Interest Rate	LIBOR plus 2.75%	LIBOR plus 2.75%
Maturity		March 2018
Mortgage Loan February [Member] | Viewmont Mall [Member]
Mortgage Loan Activity [Line Items]
Property		Viewmont Mall
Amount Financed or Extended		48.0
Stated Interest Rate		LIBOR plus 2.60%
Maturity		March 2018
Mortgage Loan March [Member] | Dartmouth Mall [Member]
Mortgage Loan Activity [Line Items]
Property		Dartmouth Mall
Amount Financed or Extended		$ 67.0
Stated Interest Rate		3.97% fixed
Maturity		April 2018