Subsequent Events Subsequent Events (Details) - USD ($) $ in Millions	Oct. 25, 2017	Sep. 30, 2017
Subsequent Event [Line Items]
Commercial paper borrowing capacity	$ 1,500.0	$ 1,000.0
Committed credit facility [Member]
Subsequent Event [Line Items]
Line of credit facility, current borrowing capacity	$ 1,500.0	$ 1,000.0

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant