v3.7.0.1

Equity-Based Compensation (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2017
Equity-Based Compensation |
Summary of restricted unit and phantom unit awards activity |
|  |  |  | Weighted average |  | Aggregate |
|  | Number of units |  | grant date fair value |  | intrinsic value (in thousands) |
Total awarded and unvested—December 31, 2016 |  | 1,331,961 |  | $ | 27.31 |  | $ | 41,131 |
Granted |  | 340,773 |  | $ | 32.45 |  |  |  |
Vested |  | (73,080) |  | $ | 21.34 |  |  |  |
Forfeited |  | (48,760) |  | $ | 28.85 |  |  |  |
Total awarded and unvested—June 30, 2017 |  | 1,550,894 |  | $ | 28.68 |  | $ | 51,459 |

X
- Definition Represents the phantom and restricted unit award activity under the equity based compensation plan. + References No definition available. + Details
Name: | am_ScheduleOfEquityBasedCompensationByEquityBasedPaymentAwardPhantomAndRestrictedUnits
Namespace Prefix: | am_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration