Summary of Net Properties and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017
Property Plant And Equipment [Abstract]
Vessels and related equipment	$ 3,180,228	$ 3,407,760
Other properties and equipment	69,605	69,670
Properties and equipment, gross	3,249,833	3,477,430
Less accumulated depreciation and amortization	590,519	612,668
Net properties and equipment	$ 2,659,314	$ 2,864,762

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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- Definition

Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

+ References

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- References

No definition available.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

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