v3.19.3.a.u2

Acquisitions and divestments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2019
South Carolina Biomass Plant |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Schedule of preliminary purchase price allocation for the business combination |
Fair values |  |  |
Cash(1) |  | $ | 1.4
Accounts receivable |  |  | 4.3
Inventory |  |  | 2.9
Property, plant, and equipment |  |  | 4.0
Intangible assets |  |  | 2.6
Accounts payable |  |  | (2.0)
Accrued liabilities |  |  | (0.3)
Other liabilities |  |  | (0.3)
Total purchase consideration |  | $ | 12.6
| (1) |  | The cash acquired was received in October 2019 and has been included in the Cash paid for acquisition, net of cash received within the Statement of Cash Flows.
Koma Kulshan Associates |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Schedule of preliminary purchase price allocation for the business combination |
Fair value of consideration transferred: |  |  |
Cash |  | $ | 12.5
Other items to be allocated to identifiable assets acquired and liabilities assumed: |  |  |
Book value of our investment in Koma at the acquisition date |  |  | 5.4
Gain recognized from step acquisition |  |  | 7.2
Total purchase price |  | $ | 25.1
Final purchase price allocation |  |  |
Cash |  | $ | 0.8
Working capital |  |  | 0.1
Property, plant, and equipment |  |  | 1.2
Intangible assets |  |  | 24.8
Asset retirement obligation |  |  | (1.8)
Total identifiable net assets |  | $ | 25.1

X
- 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. + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed. May include but not limited to the following: (a) acquired receivables; (b) contingencies recognized at the acquisition date; and (c) the fair value of noncontrolling interests in the acquiree. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472 + Details
Name: | us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=at_SouthCarolinaBiomassPlantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=at_KomaKulshanAssociatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |