Derivative Instruments (Additional Information) (Detail) $ in Thousands	3 Months Ended		24 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2011 USD ($) instrument
Derivative [Line Items]
Amortization of interest expense	$ 378	$ 434
Amount to be recognized from hedged transactions within 12 months, approximate	$ 6,800
4.2% Senior Notes, due December 2021
Derivative [Line Items]
Interest rate on senior notes	4.20%		4.20%
4.5% Senior Notes, due December 2020
Derivative [Line Items]
Interest rate on senior notes	4.50%		4.50%
Interest Rate Contract
Derivative [Line Items]
Number of instruments held | instrument			2
Interest Rate Exchange Agreement Expiring 2010 and 2011
Derivative [Line Items]
Amortization of interest expense			$ 68,900
Term of amortized interest expense, years			10 years