Consolidated Variable Interest Entities - Balance Sheets (Details) - Variable Interest Entity, Primary Beneficiary - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
EQGP and EQM | Cash and cash equivalents
Variable Interest Entity [Line Items]
Assets	$ 9,301	$ 2,857
EQGP and EQM | Accounts receivable
Variable Interest Entity [Line Items]
Assets	29,481	28,804
EQGP and EQM | Prepaid expenses and other
Variable Interest Entity [Line Items]
Assets	12,860	8,470
EQGP and EQM | Property, plant and equipment, net
Variable Interest Entity [Line Items]
Assets	2,864,040	2,804,059
EQGP and EQM | Other assets
Variable Interest Entity [Line Items]
Assets	568,594	483,004
EQGP and EQM | Accounts payable
Variable Interest Entity [Line Items]
Liabilities	48,212	47,042
EQGP and EQM | Other current liabilities
Variable Interest Entity [Line Items]
Liabilities	92,667	133,531
EQGP and EQM | Credit facility borrowings
Variable Interest Entity [Line Items]
Liabilities	317,000	180,000
EQGP and EQM | Senior Notes
Variable Interest Entity [Line Items]
Liabilities	987,756	987,352
EQGP and EQM | Other liabilities and credits
Variable Interest Entity [Line Items]
Liabilities	20,880	20,273
RMP | Cash and cash equivalents
Variable Interest Entity [Line Items]
Assets	46,518	10,538
RMP | Accounts receivable
Variable Interest Entity [Line Items]
Assets	7,205	12,246
RMP | Prepaid expenses and other
Variable Interest Entity [Line Items]
Assets	2,208	1,327
RMP | Property, plant and equipment, net
Variable Interest Entity [Line Items]
Assets	1,440,196	1,431,802
RMP | Goodwill
Variable Interest Entity [Line Items]
Assets	1,346,918	1,346,918
RMP | Other assets
Variable Interest Entity [Line Items]
Assets	6,123	0
RMP | Accounts payable
Variable Interest Entity [Line Items]
Liabilities	22,312	24,634
RMP | Other current liabilities
Variable Interest Entity [Line Items]
Liabilities	4,530	4,200
RMP | Credit facility borrowings
Variable Interest Entity [Line Items]
Liabilities	325,000	286,000
RMP | Other liabilities and credits
Variable Interest Entity [Line Items]
Liabilities	9,465	9,360
Strike Force Midstream Holdings | Cash and cash equivalents
Variable Interest Entity [Line Items]
Assets	22,136	43,938
Strike Force Midstream Holdings | Accounts receivable
Variable Interest Entity [Line Items]
Assets	20,193	12,477
Strike Force Midstream Holdings | Property, plant and equipment, net
Variable Interest Entity [Line Items]
Assets	377,112	356,346
Strike Force Midstream Holdings | Intangible assets, net
Variable Interest Entity [Line Items]
Assets	450,291	457,992
Strike Force Midstream Holdings | Other assets
Variable Interest Entity [Line Items]
Assets	107	0
Strike Force Midstream Holdings | Other current liabilities
Variable Interest Entity [Line Items]
Liabilities	$ 12,874	$ 24,341