Schedule of Other Accruals Recorded in Current Liabilities (Parenthetical) (Detail)	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Maximum percentage accounted by individual expenses of total current liabilities	5.00%	5.00%

Maximum percentage accounted by individual item of current liabilities.

No definition available.

Name:	grub_MaximumPercentageAccountedByIndividualItemOfCurrentLiabilities
Namespace Prefix:	grub_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant