Schedule of Segment Reporting Information, Revenue by Vessel Class (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 212,908	$ 378,126	$ 775,352	$ 1,150,588
Americas Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 49,792	$ 94,298	$ 191,720	$ 267,983
Percentage of revenue	23.00%	25.00%	25.00%	23.00%
Americas Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 22,254	$ 33,607	$ 75,890	$ 97,511
Percentage of revenue	11.00%	9.00%	10.00%	9.00%
Americas Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 3,917	$ 6,649	$ 11,735	$ 23,056
Percentage of revenue	2.00%	2.00%	1.00%	2.00%
Americas Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 75,963	$ 134,554	$ 279,345	$ 388,550
Percentage of revenue	36.00%	36.00%	36.00%	34.00%
Asia and Pacific Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 13,267	$ 20,575	$ 56,535	$ 72,492
Percentage of revenue	6.00%	5.00%	7.00%	6.00%
Asia/Pacific Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 5,877	$ 13,487	$ 22,719	$ 45,862
Percentage of revenue	3.00%	4.00%	3.00%	4.00%
Asia and Pacific Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues		$ 984		$ 2,930
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	$ 19,144	$ 35,046	$ 79,254	$ 121,284
Percentage of revenue	9.00%	9.00%	10.00%	10.00%
Middle East/North Africa Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 17,690	$ 25,615	$ 58,845	$ 64,336
Percentage of revenue	9.00%	7.00%	8.00%	6.00%
Middle East/North Africa Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 21,795	$ 29,441	$ 71,898	$ 93,435
Percentage of revenue	10.00%	8.00%	9.00%	8.00%
Middle East and North Africa Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 699	$ 869	$ 2,043	$ 2,530
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%	1.00%
Middle East/North Africa fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 40,184	$ 55,925	$ 132,786	$ 160,301
Percentage of revenue	19.00%	15.00%	17.00%	14.00%
Sub-Saharan Africa/Europe Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 30,361	$ 81,129	$ 124,282	$ 262,013
Percentage of revenue	14.00%	21.00%	16.00%	23.00%
Sub-Saharan Africa/Europe Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 35,186	$ 52,532	$ 118,490	$ 162,585
Percentage of revenue	16.00%	14.00%	15.00%	14.00%
Sub Saharan Africa And Europe Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 12,070	$ 18,940	$ 41,195	$ 55,855
Percentage of revenue	6.00%	5.00%	6.00%	5.00%
Sub-Saharan Africa/Europe Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 77,617	$ 152,601	$ 283,967	$ 480,453
Percentage of revenue	36.00%	40.00%	37.00%	42.00%
Worldwide Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 111,110	$ 221,617	$ 431,382	$ 666,824
Percentage of revenue	52.00%	58.00%	56.00%	58.00%
Worldwide Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 85,112	$ 129,067	$ 288,997	$ 399,393
Percentage of revenue	40.00%	35.00%	37.00%	35.00%
Worldwide Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 16,686	$ 27,442	$ 54,973	$ 84,371
Percentage of revenue	8.00%	7.00%	7.00%	7.00%
Worldwide Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 212,908	$ 378,126	$ 775,352	$ 1,150,588
Percentage of revenue	100.00%	100.00%	100.00%	100.00%