DERIVATIVES AND HEDGE ACCOUNTING ACTIVITIES - Schedule of Fair Values of Derivatives and Balance Sheet Location (Details) $ in Millions	Dec. 31, 2016 USD ($)
Derivatives, Fair Value [Line Items]
Derivatives assets	$ 0.1
Derivative liabilities	0.1
Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	0.1	[1]
Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0.1	[2]
Fair Value - Derivatives not under Hedge Accounting
Derivatives, Fair Value [Line Items]
Derivatives assets	0.1
Derivative liabilities	0.1
Fair Value - Derivatives not under Hedge Accounting | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	0.1	[1]
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0.1	[2]
Commodity | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	0.1
Commodity | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	0.1
Commodity | Fair Value - Derivatives not under Hedge Accounting | Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	0.1
Commodity | Fair Value - Derivatives not under Hedge Accounting | Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 0.1

[1] Current derivative assets are presented in prepaid expenses and other current assets in Questar Gas’ Balance Sheets.

[2] Current derivative liabilities are presented in other current liabilities in Questar Gas’ Balance Sheets.