Financing Arrangements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Mar. 19, 2012
Tranche A and Tranche A-1 term loan [Member]
Long Term Debt And Other Financing Arrangement [Line Items]
Principal available	$ 25.0	$ 25.0
Loans outstanding	0	0
Tranche B term loan [Member]
Long Term Debt And Other Financing Arrangement [Line Items]
Principal available	100.0	100.0
Loans outstanding	$ 0	$ 0