Components of Working Capital - Accrued Liabilities Table (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Components Of Working Capital [Abstract]
Accrued interest expense		$ 54,556	$ 40,646
Short-term asset retirement obligations	[1]	42,872	2,304
Short-term remediation and reclamation obligations		833	833
Income taxes payable		247	2,495
Contract liabilities		8,031	0
Other		7,965	1,714
Total accrued liabilities	[2]	114,504	$ 47,992
Liabilities incurred		$ 40,200

[1] As of September 30, 2018, includes $40.2 million of short-term liabilities incurred during the second quarter of 2018 related to the shutdowns at the Third Creek and Kitty Draw gathering systems. See Note 1 for further information.

[2] Accrued liabilities includes affiliate amounts of $2.3 million and $0.2 million as of September 30, 2018, and December 31, 2017, respectively.