Commitments And Contingencies (Narrative) (Details) $ in Millions	Sep. 30, 2017 USD ($)
Loss Contingencies [Line Items]
Amount of potential cash payments that could result from unrecognized tax benefits	$ 122
Unrecorded Unconditional Purchase Obligation Payable in Common Stock Per Year \| Maximum
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation	10
Unrecorded Unconditional Purchase Obligation Payable in Common Stock \| Maximum
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation	$ 32

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77896938&loc=d3e25336-109308

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