Summary of Debt Outstanding (Detail) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Dec. 31, 2015	Mar. 31, 2015
Term Loan Facility
Debt [Line Items]
Term loan agreement	[1]	$ 300,000	$ 300,000
Revolving Credit Agreement
Debt [Line Items]
Revolving line of credit	[1],[2]		20,000
September 2013 Senior Unsecured Notes
Debt [Line Items]
Aggregate debt outstanding		$ 500,000	$ 500,000
Weighted average remaining life in years		7 years 7 months 6 days	8 years 4 months 24 days
Weighted average coupon rate on notes outstanding		4.86%	4.86%
Fair value of debt outstanding (Level 2)		$ 425,950	$ 516,879
August 2011 Senior Unsecured Notes
Debt [Line Items]
Aggregate debt outstanding		$ 165,000	$ 165,000
Weighted average remaining life in years		4 years 9 months 18 days	5 years 7 months 6 days
Weighted average coupon rate on notes outstanding		4.42%	4.42%
Fair value of debt outstanding (Level 2)		$ 147,081	$ 167,910
September 2010 Senior Unsecured Notes
Debt [Line Items]
Aggregate debt outstanding	[3]	$ 382,500	$ 425,000
Weighted average remaining life in years	[3]	4 years 3 months 18 days	4 years 7 months 6 days
Weighted average coupon rate on notes outstanding	[3]	4.35%	4.25%
Fair value of debt outstanding (Level 2)	[3]	$ 344,634	$ 431,296
July 2003 Senior Unsecured Notes
Debt [Line Items]
Aggregate debt outstanding	[4]		$ 35,000
Weighted average remaining life in years	[4]	0 years	3 months 18 days
Weighted average coupon rate on notes outstanding	[4]		4.61%
Fair value of debt outstanding (Level 2)	[4]		$ 35,197
May 2015 United States Dollar Denominated Borrowing Agreement
Debt [Line Items]
Fair value of debt outstanding (Level 2)	[5],[6]	$ 30,047
Amount outstanding	[5],[6]	30,033
March 2015 United States Dollar Denominated Borrowing Agreement
Debt [Line Items]
Fair value of debt outstanding (Level 2)	[6]	28,265	29,501
Amount outstanding	[6]	$ 28,259	$ 29,488

[1] Fair values approximate carrying values because the borrowings bear interest at variable rates.

[2] $600 million and $580 million was available under the revolver at December 31, 2015 and March 31, 2015, respectively.

[3] Principal repayments of $42.5 million were paid during the quarter ended December 31, 2015.

[4] Remaining $35 million of borrowings fully paid in July 2015.

[5] In May 2015, a wholly owned subsidiary of the company entered into a $31.3 million, U.S. dollar denominated, 12 year borrowing agreement which matures in April 2027 and is secured by a guarantee by Tidewater Inc. The loan requires semi-annual principal payments of $1.3 million (plus accrued interest) and bears interest at a fixed rate of 2.92% plus a spread based on Tidewater Inc.’s consolidated funded indebtedness to total capitalization ratio (currently equal to 1.30% for a total rate of 4.22%).

[6] Notes require semi-annual principal payments.