STATEMENTS OF CONSOLIDATED EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Natural gas, tax (benefit)	$ (3,191)	$ (36,296)	$ (102,271)
Interest rate, tax	105	104	100
Pension and other post-retirement benefits liability adjustment, tax (benefit) expense	$ 193	$ 6,778	$ (564)
Dividends (in dollars per share)	$ 0.12	$ 0.12	$ 0.12
Common stock, authorized shares (in shares)	320,000,000	320,000,000	320,000,000
Preferred stock, authorized shares (in shares)	3,000,000	3,000,000	3,000,000
Preferred stock, shares issued (in shares)	0	0	0
Preferred shares, shares outstanding (in shares)	0	0	0
EQM
Distributions to noncontrolling interests (in dollars per common unit)	$ 3.655	$ 3.05	$ 2.505
EQGP
Distributions to noncontrolling interests (in dollars per common unit)	$ 0.806	$ 0.571	$ 0.15139