Annual Amortization of Term Loan Facility (Detail) (Line of Credit, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Debt Instrument [Line Items]
Amortization payments	$ 300
2012
Debt Instrument [Line Items]
Amortization payments	2
2013
Debt Instrument [Line Items]
Amortization payments	3
2014
Debt Instrument [Line Items]
Amortization payments	3
2015
Debt Instrument [Line Items]
Amortization payments	3
2016
Debt Instrument [Line Items]
Amortization payments	3
2017
Debt Instrument [Line Items]
Amortization payments	3
2018
Debt Instrument [Line Items]
Amortization payments	3
2019
Debt Instrument [Line Items]
Amortization payments	$ 280