Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group Including Discontinued Operation Revenue	$ 0	$ 10	$ 0	$ 4,674
Disposal Group, Including Discontinued Operation, Cost of Revenue	0	(333)	22	11,027
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0	0	0	2,085
Disposal Group, Including Discontinued Operation, General and Administrative Expense	345	284	749	1,724
Disposal Group, Including Discontinued Operation, Other Income	0		0
Disposal Group, Including Discontinued Operation, Other Expense		55		78
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax	(345)	4	(771)	(10,240)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	0	(25)	0	(33,813)
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	(345)	(21)	(771)	(44,053)
Discontinued Operation, Tax Effect of Discontinued Operation	0	0	0	(2,326)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(345)	(21)	(771)	(41,727)
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	0		0		$ 1,340
Disposal Group, Including Discontinued Operation, Other Assets, Current	0		0		14
Disposal Group, Including Discontinued Operation, Assets, Current	0		0		1,354
Disposal Group, Including Discontinued Operation, Accounts Payable, Current	817		817		740
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current	1,693		1,693		3,405
Disposal Group, Including Discontinued Operation, Liabilities, Current	2,510		2,510		4,145
Maritech [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group Including Discontinued Operation Revenue	0	0	0	187
Disposal Group, Including Discontinued Operation, Cost of Revenue	0	(98)	0	139
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0	0	0	212
Disposal Group, Including Discontinued Operation, General and Administrative Expense	0	0	0	187
Disposal Group, Including Discontinued Operation, Other Income	0		0
Disposal Group, Including Discontinued Operation, Other Expense		0		0
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax	0	98	0	(351)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	0		0		1,340
Disposal Group, Including Discontinued Operation, Other Assets, Current	0		0		0
Disposal Group, Including Discontinued Operation, Assets, Current	0		0		1,340
Disposal Group, Including Discontinued Operation, Accounts Payable, Current	0		0		0
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current	733		733		2,075
Disposal Group, Including Discontinued Operation, Liabilities, Current	733		733		2,075
Offshore Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group Including Discontinued Operation Revenue	0	10	0	4,487
Disposal Group, Including Discontinued Operation, Cost of Revenue	0	(235)	22	10,888
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0	0	0	1,873
Disposal Group, Including Discontinued Operation, General and Administrative Expense	345	284	749	1,537
Disposal Group, Including Discontinued Operation, Other Income	0		0
Disposal Group, Including Discontinued Operation, Other Expense		55		78
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax	(345)	$ (94)	(771)	$ (9,889)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	0		0		0
Disposal Group, Including Discontinued Operation, Other Assets, Current	0		0		14
Disposal Group, Including Discontinued Operation, Assets, Current	0		0		14
Disposal Group, Including Discontinued Operation, Accounts Payable, Current	817		817		740
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current	960		960		1,330
Disposal Group, Including Discontinued Operation, Liabilities, Current	$ 1,777		$ 1,777		$ 2,070