Accumulated Other Comprehensive Income - Tax Effects on Each Component of Other Comprehensive Income Recognized in Statements of Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement Of Income And Comprehensive Income [Abstract]
Foreign currency cumulative translation adjustments, Before Tax	$ (65.0)	$ 28.1
Unrealized cash flow hedge gains, Before Tax	44.8	8.0
Reclassification adjustments on foreign currency hedges, Before Tax	5.5	3.9
Unrealized gains on securities, Before Tax	(0.1)	0.2
Adjustments to prior service cost and unrecognized actuarial assumptions, Before Tax	3.7	40.9
Total Other Comprehensive Gain/(Loss), Before Tax	(11.1)	81.1
Foreign currency cumulative translation adjustments, Tax
Unrealized cash flow hedge gains, Tax	15.6	3.9
Reclassification adjustments on foreign currency hedges, Tax	1.6	3.0
Unrealized gains on securities, Tax
Adjustments to prior service cost and unrecognized actuarial assumptions, Tax	(0.5)	18.0
Total Other Comprehensive Gain/(Loss), Tax	16.7	24.9
Foreign currency cumulative translation adjustments, net of tax	(65.0)	28.1
Unrealized cash flow hedge gains net of tax	29.2	4.1
Reclassification adjustments on foreign currency hedges, net of tax	3.9	0.9
Unrealized gains on securities, net of tax	(0.1)	0.2
Adjustments to prior service cost and unrecognized actuarial assumptions, net of tax	4.2	22.9
Total Other Comprehensive Gain/(Loss)	$ (27.8)	$ 56.2