Goodwill and Intangible Assets Changes in carrying amount of goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Goodwill, Beginning Balance	$ 389.2	$ 354.9
Goodwill arising from acquisition		0.0
Effect of changes in exchange rates used for translation	2.7	(18.2)
Goodwill, Ending Balance	476.3	389.2
Atlas [Member]
Goodwill, Ending Balance	1.4
Health Advances Acquisition [Member]
Goodwill arising from acquisition		52.5
ExecuPharm Inc. [Member]
Goodwill arising from acquisition	58.6
TMAC [Member] [Member]
Goodwill arising from acquisition	25.8
CRS [Member]
Goodwill, Beginning Balance	141.8	143.8
Effect of changes in business segments		3.9
Effect of changes in exchange rates used for translation	1.6	(5.9)
Goodwill, Ending Balance	227.8	141.8
CRS [Member] \| Health Advances Acquisition [Member]
Goodwill arising from acquisition		0.0
CRS [Member] \| ExecuPharm Inc. [Member]
Goodwill arising from acquisition	58.6
PC [Member]
Goodwill, Beginning Balance	67.1	20.6
Effect of changes in business segments		(3.9)
Effect of changes in exchange rates used for translation	2.9	(2.1)
Goodwill, Ending Balance	70.0	67.1
PC [Member] \| Health Advances Acquisition [Member]
Goodwill arising from acquisition		52.5
PC [Member] \| ExecuPharm Inc. [Member]
Goodwill arising from acquisition	0.0
PC [Member] \| TMAC [Member] [Member]
Goodwill arising from acquisition	0.0
PI [Member]
Goodwill, Beginning Balance	180.3	190.5
Effect of changes in business segments		0.0
Effect of changes in exchange rates used for translation	(1.8)	(10.2)
Goodwill, Ending Balance	178.5	180.3
PI [Member] \| Health Advances Acquisition [Member]
Goodwill arising from acquisition		$ 0.0
PI [Member] \| ExecuPharm Inc. [Member]
Goodwill arising from acquisition	0.0
PI [Member] \| TMAC [Member] [Member]
Goodwill arising from acquisition	$ 0.0

PAREXEL INTERNATIONAL CORP 10-K