It represents as a cash and marketable securities held in trust account.

No definition available.

Name:	atacu_CashAndMarketableSecuritiesHeldInTrustAccount
Namespace Prefix:	atacu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair Value Measurements (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Cash and marketable securities held in Trust Account	$ 45,185,462