Derivatives - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended	9 Months Ended		9 Months Ended		9 Months Ended		3 Months Ended		1 Months Ended	3 Months Ended
	May 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Interest rate swaps [Member] Agreement	Sep. 30, 2013 Interest Rate Swap Twelve [Member]	Sep. 30, 2013 Forward Starting Interest Rate Swaps [Member] Agreement	Sep. 30, 2013 Forward Starting Interest Rate Swaps Two [Member]	Sep. 30, 2013 Settled Interest Rate Swaps [Member]	Sep. 30, 2013 Logan Valley Mall [Member]	Sep. 30, 2013 Other Malls [Member]	May 31, 2013 Jacksonville [Member]	Sep. 30, 2013 Jacksonville [Member]
Derivative Instruments [Line Items]
Derivative Instruments, Loss Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing	$ 3.4	$ 0.7	$ 0						$ 0.5	$ 0.2	$ 2.9
Loss recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)												2.9
Estimate increase to interest expense		2.8
Number of derivative, interest rate swap agreement				6		2
Derivative, Weighted average interest rate				2.54%		1.12%
Derivative, notional amount				198.8		103.0
Maturity Date					Jan. 01, 2018		Jan. 01, 2018
Unrealized loss on derivatives				1.0
Net loss								4.6
Amortized period								10 years
Fair value of derivatives in a net liability position		1.0
Termination value		$ 1.3