Segment Information - Consolidated Revenue Information by Geographic Area (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segments Geographical Areas [Abstract]
Revenues	$ 1,213.6	$ 1,175.1	$ 2,355.7	$ 2,301.8
United States [Member]
Segments Geographical Areas [Abstract]
Revenues	637.9	625.4	1,250.0	1,223.1
International [Member]
Segments Geographical Areas [Abstract]
Revenues	575.7	549.7	1,105.7	1,078.7
International [Member] | EMEA [Member]
Segments Geographical Areas [Abstract]
Revenues	362.7	356.1	695.3	703.4
International [Member] | Asia Pacific [Member]
Segments Geographical Areas [Abstract]
Revenues	140.8	123.7	273.0	243.9
International [Member] | Americas [Member]
Segments Geographical Areas [Abstract]
Revenues	$ 72.2	$ 69.9	$ 137.4	$ 131.4