Schedule of Unrecognized Tax Benefits [Line Items]

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)(1)
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- Definition

Amount of increase in unrecognized tax benefits resulting from acquisitions.

+ References

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Schedule of Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Mar. 31, 2017
Schedule Of Unrecognized Tax Benefits [Line Items]
Begining Balance		$ 402,868	$ 404,571
Additions based on tax positions related to the current year		170
Additions based on tax positions related to a prior year		2,578	6,903
Settlement and lapse of statute of limitations		(1,045)	(2,953)
Reductions based on tax positions related to a prior year			(18,086)
Ending Balance	$ 402,868	404,571	399,292
Predecessor
Schedule Of Unrecognized Tax Benefits [Line Items]
Begining Balance	400,818	$ 402,868		$ 401,375
Additions based on tax positions related to the current year	2,050			551
Settlement and lapse of statute of limitations				(1,108)
Ending Balance	$ 402,868			$ 400,818
GulfMark
Schedule Of Unrecognized Tax Benefits [Line Items]
Additions from GulfMark business combination			$ 8,857