Schedule of Segment Reporting Information, Revenue by Vessel Class (Detail) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 583,816	$ 955,400	$ 1,468,358
Americas Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 171,334	$ 235,522	$ 353,232
Percentage of revenue	29.00%	25.00%	24.00%
Americas Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 56,561	$ 92,768	$ 125,029
Percentage of revenue	10.00%	9.00%	9.00%
Americas Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 11,948	$ 14,705	$ 27,438
Percentage of revenue	2.00%	2.00%	2.00%
Americas Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 239,843	$ 342,995	$ 505,699
Percentage of revenue	41.00%	36.00%	35.00%
Asia and Pacific Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 7,252	$ 60,853	$ 94,538
Percentage of revenue	1.00%	6.00%	6.00%
Asia/Pacific Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 18,316	$ 28,192	$ 53,281
Percentage of revenue	3.00%	3.00%	4.00%
Asia and Pacific Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues			$ 3,001
Asia and Pacific Fleet Other \| Maximum
Segment and Geographic Distribution of Operations [Line Items]
Percentage of revenue			1.00%
Asia/Pacific Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 25,568	$ 89,045	$ 150,820
Percentage of revenue	4.00%	9.00%	10.00%
Middle East Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 28,274	$ 23,596	$ 28,637
Percentage of revenue	5.00%	2.00%	2.00%
Middle East Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 60,776	$ 87,760	$ 105,642
Percentage of revenue	10.00%	10.00%	7.00%
Middle East fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 89,050	$ 111,356	$ 134,279
Percentage of revenue	15.00%	12.00%	9.00%
Africa/Europe Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 102,374	$ 205,587	$ 382,957
Percentage of revenue	18.00%	22.00%	26.00%
Africa/Europe Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 102,732	$ 153,818	$ 219,914
Percentage of revenue	18.00%	16.00%	15.00%
Africa And Europe Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 24,249	$ 52,599	$ 74,689
Percentage of revenue	4.00%	5.00%	5.00%
Africa/Europe Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 229,355	$ 412,004	$ 677,560
Percentage of revenue	40.00%	43.00%	46.00%
Worldwide Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 309,234	$ 525,558	$ 859,364
Percentage of revenue	53.00%	55.00%	58.00%
Worldwide Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 238,385	$ 362,538	$ 503,866
Percentage of revenue	41.00%	38.00%	35.00%
Worldwide Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 36,197	$ 67,304	$ 105,128
Percentage of revenue	6.00%	7.00%	7.00%
Worldwide Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 583,816	$ 955,400	$ 1,468,358
Percentage of revenue	100.00%	100.00%	100.00%