OTHER CONTINGENCIES AND COMMITMENTS (2015 Gas Transmission and Storage Rate Case and 2011-2014 Gas Transmission and Storage Capital Expenditures Audit) (Details) - Disallowance of Plant Costs - USD ($) $ in Millions	Jul. 07, 2021	Jun. 23, 2016	Jul. 31, 2020
Loss Contingencies [Line Items]
Gas transmission and storage capital disallowance		$ 696.0
Permanently disallowed capital		120.0
Amount subject to audit		$ 576.0
Capital expenditures for future recovery			$ 512.0
Loss Contingency Nature, Period One
Loss Contingencies [Line Items]
Capital expenditures for future recovery, seeking recovery			$ 416.3
Capital expenditures for future recovery, pending authorization	$ 356.3
Loss Contingency Nature, Period Two
Loss Contingencies [Line Items]
Capital expenditures for future recovery, pending authorization	$ 313.3
Capital expenditures for future recovery, pending authorization, amortization period	60 months
Loss Contingency Nature, Period Three
Loss Contingencies [Line Items]
Capital expenditures for future recovery, pending authorization	$ 43.0
Capital expenditures for future recovery, pending authorization, amortization period	12 months