Intangible Assets - Schedule of Identifiable Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Definite-lived intangibles:
Customer relationships	$ 1,241.1	$ 376.6
Trade name	46.4	15.4
Non-compete agreements	16.5	9.8
Carrier relationships	12.1	12.1
Other intangible assets	2.2	2.2
Intangible assets, gross	1,318.3	416.1
Less: Accumulated amortization	(158.9)	(74.6)
Total Identifiable Intangible Assets, net	$ 1,159.4	$ 341.5