Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Aug. 23, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount interest rate swap	$ 550,000	$ 550,000
Reclassified as an increase to interest expense	1,360
Unrealized gain on derivatives, net of tax	38
Termination value of derivatives in net liability position	$ 1,634
Interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Number of outstanding interest rate derivatives	2	2