Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows From Operating Activities
Net Income	$ 39,136	$ 34,520
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Depreciation and Amortization	11,329	2,449
Dividends from Equity Method Investee, Net of Income	393	0
Unit-Based Compensation	321	127
Other Adjustments for Noncash Items Included in Income	167	95
Changes in Operating Assets and Liabilities, Net of Assets Acquired and Liabilities Assumed
Increase in Accounts Receivable	(2,520)	(3,322)
Decrease in Accounts Payable	(836)	(2,518)
Other Operating Assets and Liabilities, Net	(2,387)	874
Net Cash Provided by Operating Activities	45,603	32,225
Cash Flows From Investing Activities
Additions to Property, Plant and Equipment	(161,509)	(32,298)
Black Diamond Acquisition, Net of Cash Acquired	(650,131)	0
Additions to Investments	0	(414)
Distributions from Cost Method Investee	419	123
Net Cash Used in Investing Activities	(811,221)	(32,589)
Cash Flows From Financing Activities
Distributions to Noncontrolling Interests	(3,007)	(11,267)
Contributions from Noncontrolling Interests	409,865	7,087
Borrowings Under Revolving Credit Facility	405,000	0
Repayment of Revolving Credit Facility	(55,000)	0
Distributions to Unitholders	(19,860)	(13,782)
Revolving Credit Facility Amendment Fees and Other	(1,987)	(236)
Net Cash Provided by (Used in) Financing Activities	735,011	(18,198)
Decrease in Cash, Cash Equivalents, and Restricted Cash	(30,607)	(18,562)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	55,531	57,421
Cash, Cash Equivalents, and Restricted Cash at End of Period	$ 24,924	$ 38,859