CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Common and preferred stock and warrants offering costs		$ 1.7
Common And Preferred Stock Offering Costs	$ 2.6
Warrants issuance cost	$ 0.1

Common and preferred stock and warrants offering costs.

No definition available.

Name:	atec_CommonAndPreferredStockAndWarrantsOfferingCosts
Namespace Prefix:	atec_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration