Goodwill - Schedule of Goodwill (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Goodwill [Roll Forward]
Goodwill at beginning of period	$ 929.3
Acquisitions	2,508.2
Impact of foreign exchange translation	0.8
Litigation liability adjustments, net of tax	10.5
Other adjustments	(3.8)
Goodwill at end of period	3,445.0
Operating Segments | Transportation
Goodwill [Roll Forward]
Goodwill at beginning of period	577.0
Acquisitions	1,271.6
Impact of foreign exchange translation	0.3
Litigation liability adjustments, net of tax	10.5
Other adjustments	(1.6)
Goodwill at end of period	1,857.8
Operating Segments | Logistics
Goodwill [Roll Forward]
Goodwill at beginning of period	352.3
Acquisitions	1,236.6
Impact of foreign exchange translation	0.5
Litigation liability adjustments, net of tax	0.0
Other adjustments	(2.2)
Goodwill at end of period	$ 1,587.2