Customer Revenue by Classes of Similar Products or Services (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue from External Customer [Line Items]
Customer revenue	$ 882.5	$ 792.1	$ 2,450.6	$ 2,460.6
Services
Revenue from External Customer [Line Items]
Customer revenue	763.0	720.0	2,166.8	2,182.7
Technology
Revenue from External Customer [Line Items]
Customer revenue	119.5	72.1	283.8	277.9
Systems Integration and Consulting | Services
Revenue from External Customer [Line Items]
Customer revenue	263.1	227.7	690.6	674.2
Outsourcing | Services
Revenue from External Customer [Line Items]
Customer revenue	368.7	339.4	1,072.2	1,055.3
Infrastructure Services | Services
Revenue from External Customer [Line Items]
Customer revenue	83.9	104.7	265.7	315.3
Core Maintenance | Services
Revenue from External Customer [Line Items]
Customer revenue	47.3	48.2	138.3	137.9
Enterprise-Class Software And Servers | Technology
Revenue from External Customer [Line Items]
Customer revenue	107.3	54.6	260.7	246.9
Other Technology | Technology
Revenue from External Customer [Line Items]
Customer revenue	$ 12.2	$ 17.5	$ 23.1	$ 31.0