v3.10.0.1

Investments in Unconsolidated Affiliates (Details) $ in Thousands		12 Months Ended
	Feb. 06, 2017	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 mi
Investments in unconsolidated affiliates
Balance at beginning of period		$ 303,302	$ 68,299
Initial investment			153,770
Additional investments		136,475	81,234
Equity in net income of unconsolidated affiliates		40,280	20,194	$ 485
Distributions from unconsolidated affiliates		(46,415)	(20,195)	(7,702)
Balance at end of period		433,642	303,302	68,299
Summarized Financial Information of Unconsolidated Affiliates
Current assets		90,481	62,955
Noncurrent assets		1,327,947	1,052,760
Total assets		1,418,428	1,115,715
Current liabilities		76,605	39,964
Noncurrent liabilities		6,986	219
Noncontrolling interest		172,865	179,736
Partners' capital		1,161,972	895,796
Total liabilities and partners' capital		1,418,428	1,115,715
Statements of Combined Operations
Revenues		189,222	119,371	51,428
Operating expenses		75,250	40,059	12,176
Income from operations		113,972	79,312	39,252
Net income attributable to the equity method investments		131,626	88,717	3,227
Appalachia Joint venture
Equity Method Investments
Ownership percentage	50.00%
Percentage of interest held by joint venture in third party fractionator in Ohio	33.33%
Investments in unconsolidated affiliates
Balance at beginning of period		236,174
Initial investment			153,770
Additional investments		136,475	81,234
Equity in net income of unconsolidated affiliates		29,540	9,890
Distributions from unconsolidated affiliates		(36,650)	(8,720)
Balance at end of period		$ 365,539	236,174
Appalachia Joint venture | MarkWest
Equity Method Investments
Ownership percentage	50.00%
Stonewall Gas Gathering LLC
Equity Method Investments
Ownership percentage		15.00%			15.00%
Number of miles | mi					67
Investments in unconsolidated affiliates
Balance at beginning of period		$ 67,128	68,299
Equity in net income of unconsolidated affiliates		10,740	10,304
Distributions from unconsolidated affiliates		(9,765)	(11,475)
Balance at end of period		$ 68,103	$ 67,128	$ 68,299

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