Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Net book value of capitalized internally-developed software	$ 955.7		$ 955.7		$ 221.9
Depreciation	56.5	$ 10.8	98.8	$ 21.7
Software Development
Property, Plant and Equipment [Line Items]
Net book value of capitalized internally-developed software	$ 99.2		$ 99.2		$ 70.1