Schedule of Segment Reporting Information, Revenue by Vessel Class (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 955,400	$ 1,468,358	$ 1,418,461
Americas Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 235,522	$ 353,232	$ 263,750
Percentage of revenue	25.00%	24.00%	18.00%
Americas Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 92,768	$ 125,029	$ 115,055
Percentage of revenue	9.00%	9.00%	8.00%
Americas Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 14,705	$ 27,438	$ 31,926
Percentage of revenue	2.00%	2.00%	3.00%
Americas Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 342,995	$ 505,699	$ 410,731
Percentage of revenue	36.00%	35.00%	29.00%
Asia and Pacific Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 60,853	$ 94,538	$ 88,191
Percentage of revenue	6.00%	6.00%	6.00%
Asia/Pacific Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 28,192	$ 53,281	$ 62,630
Percentage of revenue	3.00%	4.00%	5.00%
Asia and Pacific Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues		$ 3,001	$ 3,797
Asia and Pacific Fleet Other | Maximum
Segment and Geographic Distribution of Operations [Line Items]
Percentage of revenue		1.00%	1.00%
Asia/Pacific Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 89,045	$ 150,820	$ 154,618
Percentage of revenue	9.00%	10.00%	11.00%
Middle East/North Africa Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 74,563	$ 85,279	$ 66,503
Percentage of revenue	8.00%	6.00%	5.00%
Middle East/North Africa Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 91,174	$ 117,232	$ 116,720
Percentage of revenue	10.00%	8.00%	8.00%
Middle East and North Africa Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 2,734	$ 3,276	$ 3,301
Middle East and North Africa Fleet Other | Maximum
Segment and Geographic Distribution of Operations [Line Items]
Percentage of revenue	1.00%	1.00%	1.00%
Middle East/North Africa fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 168,471	$ 205,787	$ 186,524
Percentage of revenue	18.00%	14.00%	13.00%
Sub-Saharan Africa/Europe Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 154,620	$ 326,315	$ 364,722
Percentage of revenue	16.00%	22.00%	26.00%
Sub-Saharan Africa/Europe Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 150,404	$ 208,324	$ 231,224
Percentage of revenue	16.00%	14.00%	16.00%
Sub Saharan Africa And Europe Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 49,865	$ 71,413	$ 70,642
Percentage of revenue	5.00%	5.00%	5.00%
Sub-Saharan Africa/Europe Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 354,889	$ 606,052	$ 666,588
Percentage of revenue	37.00%	41.00%	47.00%
Worldwide Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 525,558	$ 859,364	$ 783,166
Percentage of revenue	55.00%	58.00%	55.00%
Worldwide Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 362,538	$ 503,866	$ 525,629
Percentage of revenue	38.00%	35.00%	37.00%
Worldwide Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 67,304	$ 105,128	$ 109,666
Percentage of revenue	7.00%	7.00%	8.00%
Worldwide Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 955,400	$ 1,468,358	$ 1,418,461
Percentage of revenue	100.00%	100.00%	100.00%