Description of Business and Basis of Presentation - Impact of New Accounting Pronouncement - Statement of Operations Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenues
Product sales		$ 75,937
Expenses
Cost of product	[1]	77,799	$ 189,359
Operation and maintenance	[1]	88,279	73,760
Depreciation and amortization		76,842	69,702
Income tax (benefit) expense		1,502	3,552
Net income (loss) attributable to noncontrolling interests		49,483	26,721
Net income (loss) attributable to Western Gas Equity Partners, LP		101,005	$ 75,940
Fee Based [Member]
Revenues
Service revenues - fee and product based		338,419
Product Based [Member]
Revenues
Service revenues - fee and product based		22,593
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member]
Revenues
Product sales		292,291
Expenses
Cost of product		274,966
Operation and maintenance		88,139
Depreciation and amortization		76,153
Income tax (benefit) expense		1,509
Net income (loss) attributable to noncontrolling interests		80,448
Net income (loss) attributable to Western Gas Equity Partners, LP		71,375
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Fee Based [Member]
Revenues
Service revenues - fee and product based		342,338
Accounting Standards Update 2014-09 [Member] | Without Adoption of Topic 606 [Member] | Product Based [Member]
Revenues
Service revenues - fee and product based		0
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member]
Revenues
Product sales		(216,354)
Expenses
Cost of product		(197,167)
Operation and maintenance		140
Depreciation and amortization		689
Income tax (benefit) expense		(7)
Net income (loss) attributable to noncontrolling interests		(30,965)
Net income (loss) attributable to Western Gas Equity Partners, LP		29,630
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member] | Fee Based [Member]
Revenues
Service revenues - fee and product based		(3,919)
Accounting Standards Update 2014-09 [Member] | Effect of Change Increase/(Decrease) [Member] | Product Based [Member]
Revenues
Service revenues - fee and product based		$ 22,593

[1] Cost of product includes product purchases from Anadarko (as defined in Note 1) of $20.2 million and $16.0 million for the three months ended March 31, 2018 and 2017, respectively. Operation and maintenance includes charges from Anadarko of $20.2 million and $17.1 million for the three months ended March 31, 2018 and 2017, respectively. General and administrative includes charges from Anadarko of $11.8 million and $9.7 million for the three months ended March 31, 2018 and 2017, respectively. See Note 6.