Debt due within one year - Securitized trade receivables (Details) - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financial Instruments [Abstract]
Average interest rate throughout the year	1.74%	1.51%
Securitized trade receivables	$ 1,867	$ 1,904

Securitised Trade Receivables, Average Interest Rate During Period

No definition available.

Name:	bce_SecuritisedTradeReceivablesAverageInterestRateDuringPeriod
Namespace Prefix:	bce_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant