Revised Changes in Product Support Liabilities (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Product Warranty Liability [Line Items]
Cost accrual and revenue deferrals	$ 642.4	$ 479.6	$ 437.4
Payments and revenue recognized	(456.6)	(399.8)	(351.7)
Previously Reported
Schedule Of Product Warranty Liability [Line Items]
Cost accrual and revenue deferrals		340.4	305.4
Payments and revenue recognized		(260.6)	(219.7)
Revised
Schedule Of Product Warranty Liability [Line Items]
Cost accrual and revenue deferrals		479.6	437.4
Payments and revenue recognized		$ (399.8)	$ (351.7)