Cost Reduction Actions - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) employee	Jun. 30, 2016 USD ($) employee	Jun. 30, 2017 USD ($) employee	Jun. 30, 2016 USD ($) employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring Cost and Reserve [Line Items]
Estimated pretax restructuring charges						$ 300.0
Restructuring charges	$ 27.5	$ 10.2	$ 52.9	$ 37.1	$ 82.1	$ 118.5
Severance costs	24.2	6.5	36.7	28.6
Other expenses related to the cost reduction effort	3.3	3.7	16.2	8.5
Cost of Revenue | Services
Restructuring Cost and Reserve [Line Items]
Restructuring charges	19.1	5.1	27.6	16.6
Cost of Revenue | Technology
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.4		0.4
Selling, general and administrative expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8.2	5.5	19.5	18.8
Research and development expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.4	0.3	1.7
Other income (expense), net
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.2)		5.1
Idle leased facilities
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2.9
Other expenses related to the cost reduction effort			2.9
Contract amendment and termination
Restructuring Cost and Reserve [Line Items]
Other expenses related to the cost reduction effort	1.9		5.2
Professional fees and other
Restructuring Cost and Reserve [Line Items]
Other expenses related to the cost reduction effort	1.6		3.0
Foreign currency translation adjustment
Restructuring Cost and Reserve [Line Items]
Other expenses related to the cost reduction effort	(0.2)		5.1
Foreign currency translation adjustment | Other income (expense), net
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.2)		5.1
United States
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 4.8	$ 1.2	$ 5.3	$ 5.4
Number of employees | employee	369	69	414	244
United States | Changes in estimates
Restructuring Cost and Reserve [Line Items]
Severance costs	$ (0.1)		$ (0.2)
Non-US
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 19.8	$ 5.3	$ 24.0	$ 23.2
Number of employees | employee	301	262	376	599
Non-US | Changes in estimates
Restructuring Cost and Reserve [Line Items]
Severance costs	$ (0.3)		$ (0.6)
Non-US | Additional benefits provided in 2017
Restructuring Cost and Reserve [Line Items]
Severance costs			$ 8.2