Selected Balance Sheet Information (Details 2) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Inventory for remotely operated vehicles	$ 108,939		$ 97,313
Inventory, Work in Process and Raw Materials	85,568		117,969
Inventory	194,507		215,282
Prepaid Expense, Current	60,858		64,901
Available-for-sale Securities, Current	10,179		0
Other current assets	71,037		64,901
Intangible Assets, Net (Excluding Goodwill)	79,995		85,293
Investments and Other Noncurrent Assets	0		68,280
Cash surrender value of life insurance policies	51,131		54,987
Equity Method Investments	39,333		49,094
Deferred Income Tax Assets, Net	0		24,633
Other	31,859		34,458
Other non-current assets	202,318		316,745
Payroll and related costs	114,676		101,989
Accrued job costs	62,281		58,823
Deferred revenue, including billings in excess of revenue recognized	85,172		63,040
Accrued Income Taxes, Current	34,954		30,589
Other	95,022		95,817
Accrued Liabilities, Current	392,105	$ 324,803	350,258
Deferred Tax Liabilities, Gross, Noncurrent	18,243		42,040
Supplemental Executive Retirement Plan	42,992		45,037
Long-Term Incentive Plan	8,076		4,348
Accrued post-employment benefit obligations	3,239		3,352
Uncertain tax positions at end of year	17,903		5,566
Deferred Tax Liabilities, Noncurrent - Tax Act transition tax	7,813		0
Other	$ 30,113		30,980
Accounts Payable and Accrued Liabilities, Noncurrent			$ 131,323