Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
LTIPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,528	$ 2,619	$ 2,901
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	42	163	552
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,150	1,992	1,059
Cost of sales | LTIPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	729	720	1,075
Cost of sales | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	21	81	233
Cost of sales | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	634	617	269
Selling, general and administrative expenses | LTIPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,620	1,732	1,547
Selling, general and administrative expenses | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	20	78	306
Selling, general and administrative expenses | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,490	1,352	787
Research and development | LTIPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	179	167	279
Research and development | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1	4	13
Research and development | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 26	$ 23	$ 3