Regulatory Matters - Great Northern Transmission Line (GNTL) (Details) - Jun. 30, 2015 - Great Northern Transmission Line [Member]	Miles kV
Transmission [Line Items]
Transmission Line Length (Miles)	220
Transmission Line Capacity (kV) \| kV	500

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Balance Type:	na
Period Type:	duration