Derivative Instruments - Additional Information (Detail) (USD $)	3 Months Ended		24 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2011 Interest Rate Exchange Agreement Expiring 2010 and 2011 [Member]	Dec. 06, 2010 4.5% Senior Notes, due December 2020	Dec. 09, 2011 4.2% Senior Notes, due December 2021
Derivative [Line Items]
Interest rate on senior notes				4.50%	4.20%
Amortization of interest expense	$ 429,000	$ 425,000	$ 68,900,000
Term of amortized interest expense, years			10 years
Amount to be recognized from hedged transactions within 12 months, approximate	$ 7,200,000