Debt Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Debt Disclosure [Abstract]
Interest and debt costs incurred, net of interest capitalized	$ 53,752	$ 50,029	$ 43,814
Interest costs capitalized	10,451	13,673	11,497
Total interest and debt costs	$ 64,203	$ 63,702	$ 55,311