Reconciliation of Beginning and Ending Amount of Uncertain Tax Positions (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits [Line Items]
Unrecognized tax positions, Beginning balance	$ 205.4	$ 180.8	$ 164.2
Additions for tax positions related to the current year	49.1	48.9	31.1
Additions for tax positions of prior years	18.9	15.3	16.2
Reductions for tax positions of prior years	(20.6)	(27.3)	(9.9)
Settlements with taxing authorities	(91.5)	(2.1)
Lapse of statute of limitations	(4.7)	(10.2)	(20.8)
Unrecognized tax positions,Ending balance	$ 156.6	$ 205.4	$ 180.8