v2.4.1.9

Partnership Equity and Distributions (Details) (USD $) In Millions, except Per Share data, unless otherwise specified | 0 Months Ended | 2 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Feb. 02, 2015 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014
Partnership equity and distributions |  |  |  |
Annual cash distribution (per unit) |  | 0.68 am_LimitedPartnerMinimumAnnualDistributionPerPartnershipAgreement |  |
Cash balance to be maintained for distribution per quarter |  | $ 26 am_CashAvailableForDistributionsPerQuarter |  |
Cash balance to be maintained for distribution per year |  | $ 105 am_CashAvailableForDistributionsPerYear |  |
Pro rata cash distribution to the holders of common and subordinate units |  | 0.1955 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits |  |
Distribution Made to Limited Partner, Distributions Declared, Per Unit | $ 0.0943 us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit |  | $ 0.0943 us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit |
Above $0.1955 up to $0.2125 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Unitholders marginal percentage interest in distribution |  |  |  | 85.00%am_UnitHoldersMarginalPercentageInterestInDistributionPercentageOfLimitedPartnerInterest / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.1955UpTo0.2125Member
General Partners marginal percentage interest in distribution |  |  |  | 15.00%am_IncentiveDistributionDistributionPercentage / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.1955UpTo0.2125Member
Above $0.2125 up to $0.2550 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Unitholders marginal percentage interest in distribution |  |  |  | 75.00%am_UnitHoldersMarginalPercentageInterestInDistributionPercentageOfLimitedPartnerInterest / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2125UpTo0.2550Member
General Partners marginal percentage interest in distribution |  |  |  | 25.00%am_IncentiveDistributionDistributionPercentage / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2125UpTo0.2550Member
Above $0.2550 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Pro rata cash distribution to the holders of common and subordinate units |  |  |  | 0.2550 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2550Member
Unitholders marginal percentage interest in distribution |  |  |  | 50.00%am_UnitHoldersMarginalPercentageInterestInDistributionPercentageOfLimitedPartnerInterest / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2550Member
General Partners marginal percentage interest in distribution |  |  |  | 50.00%am_IncentiveDistributionDistributionPercentage / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2550Member
Minimum |  |  |  |
Partnership equity and distributions |  |  |  |
Minimum quarterly cash distribution (per unit) |  | 0.17 am_LimitedPartnerMinimumQuarterlyDistributionPerPartnershipAgreement / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Minimum | Above $0.1955 up to $0.2125 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Pro rata cash distribution to the holders of common and subordinate units |  |  |  | 0.1955 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits / us-gaap_RangeAxis = us-gaap_MinimumMember / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.1955UpTo0.2125Member
Minimum | Above $0.2125 up to $0.2550 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Pro rata cash distribution to the holders of common and subordinate units |  |  |  | 0.2125 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits / us-gaap_RangeAxis = us-gaap_MinimumMember / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2125UpTo0.2550Member
Maximum | Above $0.1955 up to $0.2125 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Pro rata cash distribution to the holders of common and subordinate units |  |  |  | 0.2125 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits / us-gaap_RangeAxis = us-gaap_MaximumMember / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.1955UpTo0.2125Member
Maximum | Above $0.2125 up to $0.2550 (Member) |  |  |  |
Partnership equity and distributions |  |  |  |
Pro rata cash distribution to the holders of common and subordinate units |  |  |  | 0.2550 am_LimitedPartnersProRataDistributionToHoldersOfCommonAndSubordinatedUnits / us-gaap_RangeAxis = us-gaap_MaximumMember / am_TotalQuarterlyDistributionTargetAmountAxis = am_Above0.2125UpTo0.2550Member

X
- Definition Represnts the amount of cash balance to be maintained for distribution per quarter. + References No definition available. + Details
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Namespace Prefix: | am_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represnts the amount of cash balance to be maintained for distribution per year. + References No definition available. + Details
Name: | am_CashAvailableForDistributionsPerYear
Namespace Prefix: | am_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of incentive obligation paid in cash or stock during the period to a limited liability corporation managing member or limited partnership partner, as the holder of our incentive rights ("IDRs"). + References No definition available. + Details
Name: | am_IncentiveDistributionDistributionPercentage
Namespace Prefix: | am_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents minimum annual distribution as per partnership agreement. + References No definition available. + Details
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Namespace Prefix: | am_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents minimum quarterly distribution as per partnership agreement. + References No definition available. + Details
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Namespace Prefix: | am_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the pro rata cash distribution made to the holders of common and subordinated units. + References No definition available. + Details
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Namespace Prefix: | am_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represnts the unitholders marginal percentage interest in distribution. + References No definition available. + Details
Name: | am_UnitHoldersMarginalPercentageInterestInDistributionPercentageOfLimitedPartnerInterest
Namespace Prefix: | am_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per unit of ownership amount of cash distributions declared to unit-holder of a limited partnership (LP). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055 + Details
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Period Type: | duration

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- Details
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Balance Type: | na
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- Details
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- Details
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Balance Type: |
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- Details
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- Details
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