Common Shares - Additional Information (Detail) - shares	Jun. 29, 2021	Jun. 15, 2021	Jun. 29, 2020	Jun. 15, 2020	Apr. 30, 2021
Class of Stock [Line Items]
Normal course issuer bid share repurchase shares authorized					29,363,070
Exxon Mobil Corporation's ownership interest in Imperial					69.60%
Normal course issuer bid share repurchase term, months			12 months
Percent of total shares				4.00%
Share Repurchase Program Dated June Twenty First Two Thousand Twenty One [Member]
Class of Stock [Line Items]
Normal course issuer bid share repurchase shares authorized	35,583,671
Exxon Mobil Corporation's ownership interest in Imperial	69.60%
Normal course issuer bid share repurchase term, months	12 months
Percent of total shares		5.00%