Segment Information - By Geographic Area (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) customer	Dec. 31, 2019 USD ($) customer	Dec. 31, 2018 USD ($) customer
Financial information with respect to entity's operations by geographic area
Operating revenues	$ 443,396	$ 438,352	$ 533,931	$ 718,364	$ 714,261	$ 758,076	$ 771,406	$ 799,640	$ 2,134,043	$ 3,043,383	$ 3,057,619
Property, plant and equipment, net	3,985,707				4,930,549				$ 3,985,707	4,930,549	5,467,870
Goodwill					28,380					$ 28,380	$ 183,914
Sales Revenue | One customer
Financial information with respect to entity's operations by geographic area
Number of customers | customer									1	1	1
Sales Revenue | Customer Concentration Risk | One customer
Financial information with respect to entity's operations by geographic area
Percentage									29.00%	22.00%	24.00%
United States
Financial information with respect to entity's operations by geographic area
Operating revenues									$ 841,531	$ 1,554,442	$ 1,347,448
Property, plant and equipment, net	1,917,203				2,470,579				1,917,203	2,470,579	2,892,910
Goodwill					13,430					13,430	65,633
Outside the U.S
Financial information with respect to entity's operations by geographic area
Operating revenues									1,292,512	1,488,941	1,710,171
Property, plant and equipment, net	$ 2,068,504				2,459,970				2,068,504	2,459,970	2,574,960
Goodwill					$ 14,950					14,950	118,281
Saudi Arabia
Financial information with respect to entity's operations by geographic area
Operating revenues									$ 642,700	$ 696,400	$ 764,500