XML 251 R73.htm IDEA: XBRL DOCUMENT v3.10.0.1
Long-term assets - E.1.1. Accounting for intangible assets (Details)
 12 Months Ended
Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]  
Period for which item is expensed (less than) 1 year
New fiber cable  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 15 years
Bottom of range | Trademarks  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 1 year
Bottom of range | Customer lists  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 4 years
Bottom of range | IRUs  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 12 years
Top of range | Trademarks  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 15 years
Top of range | Customer lists  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 20 years
Top of range | IRUs  
Disclosure of detailed information about intangible assets [line items]  
Intangible assets useful lives 15 years