Debt and Credit Facilities - Other Lines of Credit (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Line Of Credit [Line Items]
Available lines of credit	$ 1,028.7	$ 1,063.2
Unused lines of credit	989.5	1,028.7
Weighted average interest rate	6.40%	6.20%
Other Lines of Credit [Member]
Line Of Credit [Line Items]
Available lines of credit	328.3	359.3
Unused lines of credit	$ 289.0	$ 328.7
Weighted average interest rate	10.20%	10.10%