The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

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Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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- Definition

The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611443-123010

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Percentage of convertible preferred unit that will be converted to common units on a designated date.

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- Definition

Third party nonoperated interest to be acquired.

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Subsequent Events - Additional Information (Details) - Subsequent Event [Member] - Western Gas Partners, LP [Member] - USD ($) $ in Millions	Feb. 22, 2017	Feb. 09, 2017
Subsequent Event [Line Items]
Cash payment		$ 155.0
Series A Preferred Units [Member] \| Series A Preferred Units February 2017 Conversion [Member]
Subsequent Event [Line Items]
Series A Preferred units, percentage converted	50.00%
Series A Preferred Units [Member] \| Series A Preferred Units May 2017 Conversion [Member]
Subsequent Event [Line Items]
Series A Preferred units, percentage converted	50.00%
Delaware Basin JV Gathering LLC [Member]
Subsequent Event [Line Items]
Percentage ownership interest acquired from a third party		50.00%
Percentage ownership interest		50.00%
Non-Operated Marcellus Interest [Member]
Subsequent Event [Line Items]
Percentage ownership interest		33.75%