Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended								1 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 CPT	Dec. 31, 2011 CPT	Jul. 02, 2011 CPT	Jun. 30, 2012 Maximum	Jun. 30, 2012 Fair Value, Inputs, Level 2	Dec. 31, 2011 Fair Value, Inputs, Level 2	Jul. 02, 2011 Fair Value, Inputs, Level 2	Apr. 30, 2011 Credit Facility	Jun. 30, 2012 Credit Facility	Jun. 30, 2012 Other Credit Facilities	May 31, 2011 Senior Notes, 5.00 Percent Due 2021	Jun. 30, 2012 Private Placement Debt Due May 2012
Debt Disclosure [Line Items]
Fair value of total debt						$ 1,299.2	$ 1,361.0	$ 1,440.1
Aggregate principal amount												500
Debt, interest rate												5.00%
Debt, maturity year												2021
Previous revolving credit facility									800
Credit facility maximum borrowing capacity									700.0		73.1
Credit facility expiration date									Apr. 28, 2016
Credit facility interest rate, before the addition of LIBOR									1.75%
Commercial paper outstanding	7.0
Long-term debt, outstanding													105
Long-term debt, maturity date													2012-05
Remaining availability under Credit Facility										487.4
Debt agreement financial covenant, leverage ratio that may not exceeded by reported date					3.5
Compliance with debt agreement financial covenants	We were in compliance with all financial covenants in our debt agreements.
Line of credit facility, amount outstanding											7.6
Capital lease obligation cost		22.0	22.7	25.6
Accumulated amortization		5.2	5.1	5.3
Future minimum lease payments	17.4
Imputed interest	$ 2.7