Ameresco, Inc. Quarterly report pursuant to Section 13 or 15(d)

Business Acquisitions and Related Transactions - Additional Information (Details)

v3.19.3

Business Acquisitions and Related Transactions - Additional Information (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jan. 31, 2019 USD ($)	Sep. 30, 2019	Sep. 30, 2019 USD ($)	Sep. 30, 2019 Agreement	Sep. 30, 2019 project
Business Acquisition [Line Items]
Measurement period adjustment			$ 719
Measurement period adjustment, hold back contingency			398
Number of projects acquired				4	4
U.S. Federal
Business Acquisition [Line Items]
Measurement period adjustment			628
Massachusetts Based Solar Operations And Maintenance Firm
Business Acquisition [Line Items]
Fair value of consideration	$ 1,279
Measurement period adjustment			$ 91
Minimum \| Solar Photovoltaic Projects
Business Acquisition [Line Items]
Estimated useful life		1 year
Maximum \| Solar Photovoltaic Projects
Business Acquisition [Line Items]
Estimated useful life		15 years

- Definition

Business Combination, Number Of Projects Acquired

+ References

No definition available.

+ Details

Name:	amrc_BusinessCombinationNumberOfProjectsAcquired
Namespace Prefix:	amrc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Goodwill, Purchase Accounting Adjustments, Hold Back Contingency

+ References

No definition available.

+ Details

Name:	amrc_GoodwillPurchaseAccountingAdjustmentsHoldBackContingency
Namespace Prefix:	amrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e961-128460

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

+ Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=amrc_USFederalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=amrc_MassachusettsBasedSolarOperationsAndMaintenanceFirmMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=amrc_SolarPhotovoltaicProjectsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: