Goodwill, Customer Relationships and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Valuation allowance, available to reduce goodwill					$ 16
Acquired finite-lived intangible asset amortization expense	$ 202	$ 52	$ 396	$ 97
Intangible assets including goodwill, noncurrent	$ 20,055		$ 20,055		$ 20,549

Aggregate carrying amount, as of the balance sheet date, of finite-lived intangible assets, indefinite-lived intangible assets, goodwill and other noncurrent assets not separately disclosed in the balance sheet.

No definition available.

+ Details

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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- Definition

The amount of the valuation allowance recorded in a business combination against deductible temporary differences for which related tax benefits will be recorded as a reduction of the acquired entity's goodwill if those tax benefits become realizable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 740
-Section 25
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109126419&loc=d3e9901-128506

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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