CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (1,646,909)	$ (38,726)	$ (141,219)	$ (171,771)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Reorganization items (non-cash)	1,368,882
Depreciation and amortization	47,447	20,131	77,045	51,332
Amortization of deferred drydocking and survey costs		206	24,886	6,961
Amortization of debt premiums and discounts		(715)	(4,877)	(1,856)
Provision for deferred income taxes	(5,543)		672	572
Gain on asset dispositions, net	(3,561)	(6,616)	(2,263)	(10,624)
Impairment of due from affiliate				20,083
Long-lived asset impairments and other	184,748	16,777	37,773	61,132
Loss on debt extinguishment				8,119
Changes in investments in, at equity, and advances to unconsolidated companies	(4,252)	(4,531)	1,039	28,177
Compensation expense – stock based	1,707	3,731	19,603	13,406
Changes in operating assets and liabilities, net:
Trade and other receivables	6,286	2,312	1,086	9,088
Changes in due to/from affiliate, net	1,301	(2,373)	22,193	28,644
Marine operating supplies	88	1,229	2,425	(1,955)
Other current assets	(1,840)	10,305	(4,120)	10,893
Accounts payable	8,157	(1,259)	(4,438)	(15,174)
Accrued expenses	17,245	(24,896)	8,189	(13,489)
Accrued property and liability losses	(822)	(176)		141
Other current liabilities	(2,337)	(4,026)	3,008	1,332
Other liabilities and deferred credits	2,884	(1,089)	1,270	(2,023)
Deferred drydocking and survey costs		(3,414)	(70,437)	(25,968)
Other, net	4,932	(2,416)	(3,258)	6,921
Net cash provided by (used in) operating activities	(21,587)	(35,546)	(31,423)	3,941
Cash flows from investing activities:
Proceeds from sales of assets	2,172	32,742	28,847	46,115
Additions to properties and equipment	(2,265)	(9,834)	(17,998)	(21,391)
Payments related to novated construction contract	5,272
Cash and cash equivalents from stock based merger				43,806
Net cash provided by investing activities	5,179	22,908	10,849	68,530
Cash flows from financing activities:
Principal payments on long-term debt	(5,124)	(1,176)	(133,693)	(105,169)
Premium paid for redemption of secured notes			(11,402)
Cash payments to General Unsecured Creditors	(122,806)	(93,719)		(8,377)
Loss on debt extinguishment				(8,119)
Cash received for issuance of common stock		2		3
Tax on share-based award			(4,467)	(4,400)
Other	(1,200)			(2,000)
Net cash used in financing activities	(129,130)	(94,893)	(149,562)	(128,062)
Net change in cash, cash equivalents and restricted cash	(145,538)	(107,531)	(170,136)	(55,591)
Cash, cash equivalents and restricted cash at beginning of period	706,404	560,866	397,744	453,335
Cash, cash equivalents and restricted cash at end of period	560,866	453,335	227,608	397,744
Cash paid during the year for:
Interest, net of amounts capitalized	1,577	8,223	32,687	32,326
Income taxes	$ 4,740	$ 4,654	$ 14,378	16,828
Supplemental disclosure of noncash investing activities:
Merger with GulfMark				285,492
Supplemental disclosure of noncash financing activities:
Common stock issued for GulfMark merger				$ 285,492