Joint Ventures (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Mar. 31, 2019		Dec. 31, 2018		Mar. 31, 2018
Assets:
Accounts receivable			$ 743,528		$ 756,320
Other current assets			164,189		177,604
Property, plant and equipment, net			5,399,514		5,467,870
Other long-term assets			289,632		263,506
Total assets (1)			7,773,684	[1]	7,853,944	[1]	$ 7,853,944
Liabilities:
Accounts payable			399,802		392,843
Accrued liabilities			298,059		417,912
Total liabilities (1)	[1]		4,713,722		4,698,757
SANAD
Assets:
Cash and cash equivalents			242,476		211,618
Accounts receivable			66,311		73,699
Other current assets			15,548		17,198
Property, plant and equipment, net			445,092		457,963
Other long-term assets			17,728		36,583
Total assets (1)			787,155		797,061
Liabilities:
Accounts payable			61,787		60,087
Accrued liabilities			13,254		8,530
Total liabilities (1)			$ 75,041		$ 68,617
Saudi Aramco | SANAD
Joint Ventures
Cash contribution for joint venture		$ 20,000
Additional contribution amount		$ 394,000
Maturity period		25 years

[1] The condensed consolidated balance sheet as of March 31, 2019 and December 31, 2018 include assets and liabilities of variable interest entities. See Note 3—Joint Ventures for additional information.