Stock-Based Compensation (Detail) - Stock-Based Compensation Expense Recognized In Consolidated Statements Of Operations (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 38.8	[1]	$ 34.7	[1]	$ 36.4	[1]
Costs of services and product development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	17.6		15.3		15.3
Selling, general, and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 21.2		$ 19.4		$ 21.1

[1] Includes charges of $14.8 million, $12.5 million, and $5.1 million in 2014, 2013 and 2012, respectively, for awards to retirement-eligible employees since these awards vest on an accelerated basis