Schedule of Segment Reporting Information, Revenue by Vessel Class (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 125,120	$ 212,908	$ 426,911	$ 775,352
Americas Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 30,846	$ 49,792	$ 108,503	$ 191,720
Percentage of revenue	25.00%	23.00%	25.00%	25.00%
Americas Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 11,905	$ 22,254	$ 41,823	$ 75,890
Percentage of revenue	9.00%	11.00%	10.00%	10.00%
Americas Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 2,826	$ 3,917	$ 8,984	$ 11,735
Percentage of revenue	2.00%	2.00%	2.00%	1.00%
Americas Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 45,577	$ 75,963	$ 159,310	$ 279,345
Percentage of revenue	36.00%	36.00%	37.00%	36.00%
Asia and Pacific Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 1,652	$ 13,267	$ 6,114	$ 56,535
Percentage of revenue	1.00%	6.00%	2.00%	7.00%
Asia/Pacific Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 3,934	$ 5,877	$ 13,503	$ 22,719
Percentage of revenue	3.00%	3.00%	3.00%	3.00%
Asia/Pacific Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 5,586	$ 19,144	$ 19,617	$ 79,254
Percentage of revenue	4.00%	9.00%	5.00%	10.00%
Middle East Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 6,953	$ 5,359	$ 19,979	$ 17,800
Percentage of revenue	6.00%	3.00%	5.00%	2.00%
Middle East Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 13,694	$ 20,897	$ 48,344	$ 69,393
Percentage of revenue	11.00%	9.00%	11.00%	9.00%
Middle East fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 20,647	$ 26,256	$ 68,323	$ 87,193
Percentage of revenue	17.00%	12.00%	16.00%	11.00%
Africa/Europe Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 21,748	$ 42,692	$ 79,342	$ 165,327
Percentage of revenue	17.00%	20.00%	18.00%	22.00%
Africa/Europe Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 26,087	$ 36,084	$ 79,938	$ 120,995
Percentage of revenue	21.00%	17.00%	19.00%	15.00%
Africa And Europe Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 5,475	$ 12,769	$ 20,381	$ 43,238
Percentage of revenue	5.00%	6.00%	5.00%	6.00%
Africa/Europe Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 53,310	$ 91,545	$ 179,661	$ 329,560
Percentage of revenue	43.00%	43.00%	42.00%	43.00%
Worldwide Fleet Deepwater vessels
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 61,199	$ 111,110	$ 213,938	$ 431,382
Percentage of revenue	49.00%	52.00%	50.00%	56.00%
Worldwide Fleet Towing-Supply/supply
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 55,620	$ 85,112	$ 183,608	$ 288,997
Percentage of revenue	44.00%	40.00%	43.00%	37.00%
Worldwide Fleet Other
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 8,301	$ 16,686	$ 29,365	$ 54,973
Percentage of revenue	7.00%	8.00%	7.00%	7.00%
Worldwide Fleet
Segment and Geographic Distribution of Operations [Line Items]
Vessel revenues	$ 125,120	$ 212,908	$ 426,911	$ 775,352
Percentage of revenue	100.00%	100.00%	100.00%	100.00%