Summary of Retirement Plan Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	$ 81.2	$ 76.8	$ 71.5
Defined contribution retirement plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	40.3	36.9	33.3
Defined benefit pension plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	33.6	37.6	31.7
Deferred compensation and excess benefit plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	5.7	0.7	4.6
Postretirement benefit plans
Schedule of Employee Benefit Plans [Line Items]
Retirement plan expense	$ 1.6	$ 1.6	$ 1.9