Income Taxes (Uncertain Tax Positions Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Income Tax Examination [Line Items]
Income Tax Examination, pre-tax adjustments proposed	$ 192
Income Tax Examination, Estimate of Possible Loss	$ 67

Estimated amount of loss resulting from an adverse tax position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration