Stock-Based Compensation (Detail) - Stock-Based Compensation Expense Recognized In Consolidated Statements Of Operations - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	[1]	$ 10.7	$ 6.9	$ 27.4	$ 20.6
Cost of services and product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		4.7	3.7	11.6	9.5
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		$ 6.0	$ 3.2	$ 15.8	$ 11.1

[1] Includes charges of $3.9 million and $2.1 million for the three months ended June 30, 2015 and 2014, respectively, and $14.4 million and $9.8 million for the six months ended June 30, 2015 and 2014, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis.