Schedule of Other Liabilities and Deferred Credits (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Mar. 31, 2016
Deferred Credits and Other Liabilities [Abstract]
Postretirement benefits liability	$ 1,872	$ 4,755
Pension liabilities	39,106	41,690
Deferred gain on vessel sales	100,822	112,721
Other	22,730	22,380
Total other liabilities and deferred credits	$ 164,530	$ 181,546