The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

Name:	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Purchase of Fixed Assets - Narrative (Details) ft² in Thousands, $ in Millions			9 Months Ended
	Apr. 01, 2016	Mar. 31, 2016 USD ($) ft²	Sep. 30, 2016 USD ($) property	Mar. 31, 2016 a
CME Group's Data Center
Business Acquisition [Line Items]
Payments for properties		$ 131.1
Area acquired (in sqft or acre)		428		15
Lease term of favorable leasehold interest which being amortized	15 years
Properties for development
Business Acquisition [Line Items]
Payments for properties			$ 54.5
Number of properties purchased \| property			4