Convertible Debentures and Credit Arrangements - Convertible Senior Debentures due 2014 - Additional Information (Detail) (Convertible Senior Debentures due 2014, USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Nov. 30, 2012
Convertible Senior Debentures due 2014
Debt Instrument [Line Items]
Aggregate face value of convertible senior debentures	$ 46.9
Repurchase of Debentures		$ 58.7