Commitments and Contingencies	3 Months Ended
Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES Litigation and legal proceedings. In February 2017, DBJV, at the time a 50/50 joint venture between a third party and WES, initiated an arbitration against SWEPI LP (“SWEPI”) for breach of a 2007 gas gathering agreement between it and DBJV (the “GGA”). Specifically, DBJV seeks to collect approximately $194.2 million in gathering fees under the GGA for the period January 1, 2016 to July 1, 2017. SWEPI disputes DBJV’s calculation of the cost of service based rate and filed a counterclaim for $14.9 million alleging overpayment of fees under the GGA for the years 2013 through 2015. The final arbitration hearing began April 30, 2018, and WES expects to receive a decision by the end of the fourth quarter of 2018. Under the terms of the Property Exchange, WES’s former joint venture partner in DBJV will owe 50% of any amounts to be paid, and have a right to 50% of any amounts received, by WES as a result of this arbitration proceeding. Pursuant to an agreement between the parties, if the arbitrators determine that DBJV is owed an amount of money by SWEPI for underpaid gathering fees for the period from January 1, 2016 to July 1, 2017, that amount will be paid to DBJV over five years as a supplemental gathering fee under the currently effective gas gathering agreement between the parties. Any other amounts owed by either party will be paid in cash within ninety days of the conclusion of the arbitration. As part of the adoption of Topic 606 (see Note 1), during the first quarter of 2018, WES recorded a $7.5 million contract liability and reduced total equity and partners’ capital related to the counterclaim for the years 2013 through 2015 under the GGA revenue contract. Any amounts awarded to DBJV under the arbitration would be recognized in the period the arbitration decision is received. WES intends to vigorously prosecute its claims and vigorously defend the counterclaims asserted by SWEPI. Management does not believe the outcome of this proceeding will have a materially unfavorable effect on the financial condition, results of operations or cash flows of WGP. In addition, from time to time, WGP, through its partnership interests in WES, is involved in legal, tax, regulatory and other proceedings in various forums regarding performance, contracts and other matters that arise in the ordinary course of business. Management is not aware of any such proceeding the final disposition of which could have a material adverse effect on the financial condition, results of operations or cash flows of WGP. Other commitments. WES has short-term payment obligations, or commitments, related to its capital spending programs, as well as those of its unconsolidated affiliates, the majority of which is expected to be paid in the next twelve months. These commitments relate primarily to construction and expansion projects at the DBJV system and the DJ Basin and DBM complexes. Lease commitments. Anadarko, on WES’s behalf, has entered into lease arrangements for corporate offices, shared field offices and equipment supporting WES’s operations, for which Anadarko charges WES lease expense. The leases for the corporate offices and shared field offices extend through 2028 and 2033, respectively. Lease expense charged to WES associated with these lease arrangements was $13.8 million and $8.6 million for the three months ended March 31, 2018 and 2017, respectively.

11. COMMITMENTS AND CONTINGENCIES

Litigation and legal proceedings. In February 2017, DBJV, at the time a 50/50 joint venture between a third party and WES, initiated an arbitration against SWEPI LP (“SWEPI”) for breach of a 2007 gas gathering agreement between it and DBJV (the “GGA”). Specifically, DBJV seeks to collect approximately $194.2 million in gathering fees under the GGA for the period January 1, 2016 to July 1, 2017. SWEPI disputes DBJV’s calculation of the cost of service based rate and filed a counterclaim for $14.9 million alleging overpayment of fees under the GGA for the years 2013 through 2015. The final arbitration hearing began April 30, 2018, and WES expects to receive a decision by the end of the fourth quarter of 2018. Under the terms of the Property Exchange, WES’s former joint venture partner in DBJV will owe 50% of any amounts to be paid, and have a right to 50% of any amounts received, by WES as a result of this arbitration proceeding. Pursuant to an agreement between the parties, if the arbitrators determine that DBJV is owed an amount of money by SWEPI for underpaid gathering fees for the period from January 1, 2016 to July 1, 2017, that amount will be paid to DBJV over five years as a supplemental gathering fee under the currently effective gas gathering agreement between the parties. Any other amounts owed by either party will be paid in cash within ninety days of the conclusion of the arbitration. As part of the adoption of Topic 606 (see Note 1), during the first quarter of 2018, WES recorded a $7.5 million contract liability and reduced total equity and partners’ capital related to the counterclaim for the years 2013 through 2015 under the GGA revenue contract. Any amounts awarded to DBJV under the arbitration would be recognized in the period the arbitration decision is received. WES intends to vigorously prosecute its claims and vigorously defend the counterclaims asserted by SWEPI. Management does not believe the outcome of this proceeding will have a materially unfavorable effect on the financial condition, results of operations or cash flows of WGP.

In addition, from time to time, WGP, through its partnership interests in WES, is involved in legal, tax, regulatory and other proceedings in various forums regarding performance, contracts and other matters that arise in the ordinary course of business. Management is not aware of any such proceeding the final disposition of which could have a material adverse effect on the financial condition, results of operations or cash flows of WGP.

Other commitments. WES has short-term payment obligations, or commitments, related to its capital spending programs, as well as those of its unconsolidated affiliates, the majority of which is expected to be paid in the next twelve months. These commitments relate primarily to construction and expansion projects at the DBJV system and the DJ Basin and DBM complexes.

Lease commitments. Anadarko, on WES’s behalf, has entered into lease arrangements for corporate offices, shared field offices and equipment supporting WES’s operations, for which Anadarko charges WES lease expense. The leases for the corporate offices and shared field offices extend through 2028 and 2033, respectively. Lease expense charged to WES associated with these lease arrangements was $13.8 million and $8.6 million for the three months ended March 31, 2018 and 2017, respectively.