v3.10.0.1

Transactions with Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allocation of costs
General and administrative expense	$ 52	$ 54	$ 50
Service
Allocation of costs
Direct labor expenses	$ 7	$ 6	$ 4

X

- Definition

Represents allocation of costs.

+ References

No definition available.

+ Details

Name:	am_AllocationOfCosts
Namespace Prefix:	am_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Cost of labor directly related to good produced and service rendered. Includes, but is not limited to, payroll cost and equity-based compensation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(2))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: