Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 484,336		$ 435,990	$ 367,693		$ 447,766
Short-term investments	9,942		16,506
Accounts receivable, net	349,005		453,042
Inventory, net	166,537		176,341
Assets held for sale	562		2,530
Other current assets	142,540		164,257
Total current assets	1,152,922		1,248,666
Property, plant and equipment, net	4,395,725		4,930,549
Goodwill			28,380
Deferred income taxes	275,719		305,844
Other long-term assets	158,049		247,219
Total assets (1)	5,982,415		6,760,658
Current liabilities:
Trade accounts payable	221,755		295,159
Accrued liabilities	274,270		333,282
Income taxes payable	17,180		14,628
Current lease liabilities	10,485		13,479
Total current liabilities	523,690		656,548
Long-term debt	3,276,103		3,333,220
Other long-term liabilities	238,205		292,184
Deferred income taxes	2,800		3,149
Total liabilities (1)	4,040,798		4,285,101
Redeemable noncontrolling interest in subsidiary	434,131		425,392
Shareholders' equity	1,413,147		1,982,811
Noncontrolling interest	94,339		67,354
Total equity	1,507,486	$ 1,641,098	2,050,165	$ 2,455,141	$ 2,650,039	$ 2,750,326
Total liabilities and equity	$ 5,982,415		$ 6,760,658