Financing Arrangements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Mar. 19, 2012
Treanche A and Tranch A-1 term loan [Member]
Long Term Debt And Other Financing Arrangement [Line Items]
Principal available	$ 25	$ 25
Loans outstanding	0	0
Tranche B Term Loan [Member]
Long Term Debt And Other Financing Arrangement [Line Items]
Principal available	100	100
Loans outstanding	$ 0	$ 0