Selected Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Inventory [Line Items]
Liability for Uncertainty in Income Taxes, Noncurrent	$ 12,000	$ 21,000
Inventory:
Remotely operated vehicle parts and components	79,570	98,624
Other inventory, primarily raw materials	68,957	76,120
Total	148,527	174,744
Other current assets:
Prepaid expenses	55,960	43,210
Angolan bonds	10,179	10,179
Total	66,139	53,389
Accrued liabilities:
Payroll and related costs	120,117	137,001
Accounts Payable, Other, Current	40,662	54,387
Income taxes payable	33,986	36,996
Current operating lease liability	20,481	19,863
Other	73,882	89,434
Total	$ 289,128	$ 337,681