Recently Issued or Adopted Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefits	$ 11
Reclassified financing activity in cash flow	(346)	$ (41)
Reclassified operating activity in cash flow	353	185
Accounting Standards Update 2016-09, Excess Tax Benefit Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassified financing activity in cash flow		(6)
Reclassified operating activity in cash flow		6
Accounting Standards Update 2016-09, Cash Flow Classifications Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassified financing activity in cash flow	$ 44	46
Reclassified operating activity in cash flow		$ (46)

Effective Income Tax Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount

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- Definition

Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

+ References

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- Definition

Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3521-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3536-108585

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