Segments and Related Information (Schedule of Significant Customers, Revenue Concentration Information) (Details) - Customer Concentration Risk [Member] - Revenue [Member]	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AT&T (including DIRECTV) [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	20.00%	23.00%	25.00%
Equitrans Midstream Corporation/EQT Corporation [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	11.00%	20.00%	0.00%
Energy Transfer Affiliates [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	8.00%	14.00%	40.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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