Company and basis of presentation.

No definition available.

Name:	atec_CompanyAndBasisOfPresentationLineItems
Namespace Prefix:	atec_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Latest effective date of minimum liquidity covenant, month and year.

+ References

No definition available.

+ Details

Name:	atec_LatestEffectiveDateOfMinimumLiquidityCovenantMonthAndYear
Namespace Prefix:	atec_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum liquidity covenant amount.

+ References

No definition available.

+ Details

Name:	atec_MinimumLiquidityCovenantAmount
Namespace Prefix:	atec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Working capital.

+ References

No definition available.

+ Details

Name:	atec_WorkingCapital
Namespace Prefix:	atec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_Cash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

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

- Definition

Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_SecuredLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis=atec_ReclassificationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_EquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=atec_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=atec_SquadronCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

The Company and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 27, 2019	Dec. 31, 2018	Nov. 06, 2018
Company And Basis Of Presentation [Line Items]
Working capital	$ 36,100
Cash	16,419			$ 29,054
Minimum liquidity covenant amount	$ 5,000
Latest effective date of minimum liquidity covenant	2020-03
Depreciation	$ 1,600	$ 1,500
Reclassification \| Surgical instruments
Company And Basis Of Presentation [Line Items]
Depreciation		$ 1,300
Term Loan \| Squadron Credit Agreement
Company And Basis Of Presentation [Line Items]
Secured debt agreement			$ 30,000		$ 35,000