Joint Ventures (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Mar. 31, 2018
Assets:
Cash and cash equivalents		$ 336,997	$ 367,039
Accounts receivable		698,477	733,541
Other current assets		180,134	156,533
Property, plant and equipment, net		6,109,565	5,969,063
Other long-term assets		252,854	245,631
Total assets	[1]	8,401,984	8,299,830
Liabilities:
Accounts payable		363,416	309,883
Accrued liabilities		533,044	432,294
Total liabilities	[1]	5,259,213	5,356,426
SANAD
Assets:
Cash and cash equivalents		94,496	120,051
Accounts receivable		10,580	19,819
Other current assets		10,834	10,046
Property, plant and equipment, net		130,218	121,408
Other long-term assets		23,091	21,921
Total assets		269,219	293,245
Liabilities:
Accounts payable		7,236	56,906
Accrued liabilities		2,592	5,808
Total liabilities		9,828	$ 62,714
Saudi Aramco | SANAD
Joint Ventures
Cash contribution for joint venture		20,000
Additional contribution amount		$ 204,000
Maturity period		25 years

[1] The condensed consolidated balance sheet as of March 31, 2018 and December 31, 2017 include assets and liabilities of variable interest entities. See Note 3—Joint Ventures for additional information.