Stock-based Compensation - Allocation of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 1,441	$ 1,242	$ 2,637	$ 2,056
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	0	0	0	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	2,705	3,175	4,234	6,421
Cost of sales | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	487	335	871	574
Cost of sales | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	0	0	0	0
Cost of sales | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	495	351	985	701
Selling, General and Administrative Expenses [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	872	840	1,603	1,361
Selling, General and Administrative Expenses [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	0	0	0	0
Selling, General and Administrative Expenses [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	2,175	2,807	3,179	5,688
Research and Development Expense [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	82	67	163	121
Research and Development Expense [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	0	0	0	0
Research and Development Expense [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 35	$ 17	$ 70	$ 32