SHORT-TERM DEBT AND CREDIT AGREEMENTS (Details)	Dec. 31, 2016 USD ($) facility
Line of Credit Facility [Line Items]
Facility Limit	$ 1,000,000,000	[1]
Outstanding Commercial Paper	200,000,000	[2]
Outstanding Letters of Credit	$ 0
Weighted average interest rate percentage	6.85%	[3]
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million
Line of Credit Facility [Line Items]
Number of joint revolving credit facilities | facility	2
Facility Limit	$ 1,000,000,000.0
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million | Line of Credit
Line of Credit Facility [Line Items]
Amount of sub-limit	250,000,000
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million | Letter of Credit
Line of Credit Facility [Line Items]
Facility Limit	$ 1,000,000,000.0
Joint Revolving Credit Facility $5 Billion and Joint Revolving Credit Facility $500 Million | Commercial Paper
Line of Credit Facility [Line Items]
Weighted average interest rate percentage	1.10%
Credit Facility $5 Billion
Line of Credit Facility [Line Items]
Facility Limit	$ 500,000,000	[1]
Outstanding Commercial Paper	200,000,000	[1],[2]
Outstanding Letters of Credit	0	[1]
Credit Facility $500 Million
Line of Credit Facility [Line Items]
Facility Limit	500,000,000	[1]
Outstanding Commercial Paper	0	[1],[2]
Outstanding Letters of Credit	$ 0	[1]

[1] A maximum of a combined $1.0 billion of the facilities is available to Questar Gas, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion, Virginia Power and Dominion Gas. Sub-limits for Questar Gas are set within the facility limit but can be changed at the option of the borrowers multiple times per year. At December 31, 2016, the sub-limit for Questar Gas was an aggregate $250 million. If Questar Gas has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany borrowings from Dominion. In May 2016, the maturity date for these facilities is April 2020. These credit facilities can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.

[2] The weighted-average interest rate of the outstanding commercial paper supported by these credit facilities was 1.10% at December 31, 2016.

[3] Represents weighted-average coupon rates for debt outstanding as of December 31, 2016.