Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Derivative	Jun. 30, 2012	Jun. 30, 2013 Derivative	Jun. 30, 2012	Dec. 31, 2012
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Change in fair value of interest-rate contracts	$ 10,890,000	$ (12,273,000)	$ 12,644,000	$ (11,007,000)
Approximate fair value of notes	267,500,000		267,500,000		250,700,000
Carrying amount of notes	265,400,000		265,400,000		250,400,000
Tax Increment Financing Bonds ("TIF Bonds")	5,149,000		5,149,000		5,247,000
Aggregate notional amount	632,100,000		632,100,000		632,800,000
Derivative financial instruments	4,400,000		4,400,000		17,100,000
Number of interest rate derivatives held	10		10
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ 6,600,000		$ 6,600,000