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Summary Debt Outstanding Based On Stated Maturities (Parenthetical) (Detail)	9 Months Ended
	Dec. 31, 2017	Jul. 31, 2017
Bank Term Loan Due July 2019
Debt [Line Items]
Debt Instrument Maturity Period	July 2019
Revolving Line Of Credit Due July 2019
Debt [Line Items]
Debt Instrument Maturity Period	July 2019
3.90% September 2010 Senior Notes Due December 2017
Debt [Line Items]
Debt Instrument Maturity Period	December 2017
Debt instrument interest rate	3.90%
3.95% September 2010 Senior Notes Due December 2017
Debt [Line Items]
Debt Instrument Maturity Period	December 2017
Debt instrument interest rate	3.95%
4.12% September 2010 Senior Notes Due December 2018
Debt [Line Items]
Debt Instrument Maturity Period	December 2018
Debt instrument interest rate	4.12%
4.17% September 2010 Senior Notes Due December 2018
Debt [Line Items]
Debt Instrument Maturity Period	December 2018
Debt instrument interest rate	4.17%
4.33% September 2010 Senior Notes Due December 2019
Debt [Line Items]
Debt Instrument Maturity Period	December 2019
Debt instrument interest rate	4.33%
4.51% September 2010 Senior Notes Due December 2020
Debt [Line Items]
Debt Instrument Maturity Period	December 2020
Debt instrument interest rate	4.51%
4.56% September 2010 Senior Notes Due December 2020
Debt [Line Items]
Debt Instrument Maturity Period	December 2020
Debt instrument interest rate	4.56%
4.61% September 2010 Senior Notes Due December 2022
Debt [Line Items]
Debt Instrument Maturity Period	December 2022
Debt instrument interest rate	4.61%
4.06% August 2011 Senior Notes Due March 2019
Debt [Line Items]
Debt Instrument Maturity Period	March 2019
Debt instrument interest rate	4.06%
4.54% August 2011 Senior Notes Due June 2021
Debt [Line Items]
Debt Instrument Maturity Period	June 2021
Debt instrument interest rate	4.54%
4.64% August 2011 Senior Notes Due June 2021
Debt [Line Items]
Debt Instrument Maturity Period	June 2021
Debt instrument interest rate	4.64%
4.26% September 2013 Senior Notes Due November 2020
Debt [Line Items]
Debt Instrument Maturity Period	November 2020
Debt instrument interest rate	4.26%
5.01% September 2013 Senior Notes Due November 2023
Debt [Line Items]
Debt Instrument Maturity Period	November 2023
Debt instrument interest rate	5.01%
5.16% September 2013 Senior Notes Due November 2025
Debt [Line Items]
Debt Instrument Maturity Period	November 2025
Debt instrument interest rate	5.16%
8.00% New Secured Notes Due August 2022
Debt [Line Items]
Debt Instrument Maturity Period	August 2022
Debt instrument interest rate	8.00%	8.00%
Norwegian Kroner Denominated Notes Due May 2024 | Troms Offshore Supply AS
Debt [Line Items]
Debt Instrument Maturity Period	May 2024
Norwegian Kroner Denominated Notes Due January 2026 | Troms Offshore Supply AS
Debt [Line Items]
Debt Instrument Maturity Period	January 2026
United States Dollar Denominated Notes Due January 2027 | Troms Offshore Supply AS
Debt [Line Items]
Debt Instrument Maturity Period	January 2027
United States Dollar Denominated Notes Due April 2027 | Troms Offshore Supply AS
Debt [Line Items]
Debt Instrument Maturity Period	April 2027

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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