Cost of Revenues - Additional Information (Detail) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2016 CNY (¥)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 CNY (¥)	Dec. 31, 2014 CNY (¥)
Cost of Revenue [Abstract]
Write-down of inventories and prepayment for vehicle purchase cost	¥ 50,190	$ 7,229	¥ 0	¥ 0

Charge to cost of goods sold that represents the reduction of carrying amount of inventory and prepaid purchase cost of inventory, generally attributable to obsolescence or market conditions.

No definition available.

Name:	athm_WritedownOfInventoriesAndPrepaymentForVehiclePurchaseCost
Namespace Prefix:	athm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration