Concentration of Risk and Segment Data - Segment Assets (Details) - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 11,175,510	$ 11,095,995
Other non-allocated assets
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,652,355	3,026,707
EMS | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,378,703	2,778,820
DMS | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 5,144,452	$ 5,290,468