Inventories (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2015
Inventories [Abstract]
Raw materials	$ 46,211		$ 46,211		$ 50,578
Work-in-progress	17,771		17,771		17,905
Finished goods	22,944		22,944		19,271
Total	86,926		86,926		87,754
Goods-in-transit included in raw materials	7,300		7,300		$ 11,900
Provisions for inventory	$ 500	$ 1,800	$ 5,491	$ 3,838