Basis of Presentation (Details) supplier in Thousands, product in Millions	12 Months Ended
Dec. 31, 2018 product supplier
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Minimum number of products offered \| product	14
Minimum number of suppliers providing products offered \| supplier	11

The minimum number of suppliers providing products offered by the entity.

No definition available.

Name:	w_MinimumNumberOfSuppliers
Namespace Prefix:	w_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration