Schedule of Segment Reporting Information, Revenue by Vessel Class (Detail) - Entity [Domain] - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2015	Jun. 30, 2014
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 298,313	$ 381,510
Americas Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 80,152	$ 82,282
Percentage of revenue	27.00%	21.00%
Americas Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 29,515	$ 29,517
Percentage of revenue	10.00%	8.00%
Americas Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 4,505	$ 8,184
Percentage of revenue	1.00%	2.00%
Americas Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 114,172	$ 119,983
Percentage of revenue	38.00%	31.00%
Asia and Pacific Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 19,833	$ 24,242
Percentage of revenue	7.00%	7.00%
Asia/Pacific Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 8,104	$ 15,037
Percentage of revenue	2.00%	4.00%
Asia and Pacific Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues		$ 970
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	$ 27,937	$ 40,249
Percentage of revenue	9.00%	11.00%
Middle East/North Africa Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 20,386	$ 19,467
Percentage of revenue	7.00%	5.00%
Middle East/North Africa Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 26,189	$ 35,279
Percentage of revenue	9.00%	9.00%
Middle East and North Africa Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 691	$ 793
Percentage of revenue	1.00%
Middle East and North Africa Fleet Other \| Maximum
Segment and Geographic Distribution of Operations [Line Items]
Percentage of revenue		1.00%
Middle East/North Africa fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 47,266	$ 55,539
Percentage of revenue	16.00%	15.00%
Sub-Saharan Africa/Europe Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 53,966	$ 91,691
Percentage of revenue	18.00%	24.00%
Sub-Saharan Africa/Europe Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 41,198	$ 55,436
Percentage of revenue	14.00%	14.00%
Sub Saharan Africa And Europe Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 13,774	$ 18,612
Percentage of revenue	5.00%	5.00%
Sub-Saharan Africa/Europe Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 108,938	$ 165,739
Percentage of revenue	37.00%	43.00%
Worldwide Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 174,337	$ 217,682
Percentage of revenue	59.00%	57.00%
Worldwide Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 105,006	$ 135,269
Percentage of revenue	35.00%	35.00%
Worldwide Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 18,970	$ 28,559
Percentage of revenue	6.00%	8.00%
Worldwide Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 298,313	$ 381,510
Percentage of revenue	100.00%	100.00%