XML 76 R53.htm IDEA: XBRL DOCUMENT v3.10.0.1
ORGANIZATION - Ownership Interests in Natural Gas Pipeline Systems (Details)
12 Months Ended
Dec. 31, 2018
LimitedPartnership
mi
Organization  
Number of intermediate limited partnerships through which pipeline assets are owned | LimitedPartnership 3
GTN  
Organization  
Length of pipeline owned (in miles) 1,377
Ownership interest (as a percent) 100.00%
Bison  
Organization  
Length of pipeline owned (in miles) 303
Ownership interest (as a percent) 100.00%
North Baja  
Organization  
Length of pipeline owned (in miles) 86
Ownership interest (as a percent) 100.00%
Tuscarora  
Organization  
Length of pipeline owned (in miles) 305
Ownership interest (as a percent) 100.00%
Northern Border  
Organization  
Length of pipeline owned (in miles) 1,412
Ownership interest (as a percent) 50.00%
Northern Border | ONEOK Partners, L.P.  
Organization  
Remaining ownership interest (as a percent) 50.00%
PNGTS  
Organization  
Length of pipeline owned (in miles) 295
Ownership interest (as a percent) 61.71%
PNGTS | Maritimes and Northeast Pipeline LLC  
Organization  
Length of pipeline owned (in miles) 107
Ownership interest (as a percent) 32.00%
Great Lakes  
Organization  
Length of pipeline owned (in miles) 2,115
Ownership interest (as a percent) 46.45%
Great Lakes | TransCanada  
Organization  
Remaining noncontrolling ownership interest (as a percent) 53.55%
Iroquois Gas  
Organization  
Length of pipeline owned (in miles) 416
Ownership interest (as a percent) 49.34%
Iroquois Gas | TransCanada  
Organization  
Ownership interest (as a percent) 0.66%
Iroquois Gas | Dominion Midstream  
Organization  
Ownership interest (as a percent) 25.93%
Iroquois Gas | Dominion Resources  
Organization  
Ownership interest (as a percent) 24.07%
Iroquois Gas | TransCanada  
Organization  
Remaining ownership interest (as a percent) 50.66%
Northern New England Investment | PNGTS  
Organization  
Remaining noncontrolling ownership interest (as a percent) 38.29%