Income Taxes - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Operating Loss Carryforwards [Line Items]
Foreign withholding related taxes		$ 2,440,000
Tax effect from change in tax rate		(231,000)
Unrecognized tax benefits, decrease resulting from prior period tax positions		475,000
Liability for unrecognized tax benefits		2,894,000	$ 2,419,000	$ 4,762,000
Income tax examination, interest accrued		209,000	213,000
Income tax examination, interest expense		19,000	86,000	57,000
Income tax examination, penalty accrued		0	0	0
Income tax examination, penalty expense		$ 0	$ 0	$ 0
Period within which the company does not anticipate total unrecognized tax benefits to change		within the next twelve months
Federal corporate tax rate	35.00%	21.00%	31.50%	35.00%
Income tax expense due to tax reform		$ 210,000	$ 1,381,000
Research and Development
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount		11,072,000	5,368,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		17,419,000	36,395,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		1,662,000
Tax effect from change in tax rate		500,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Income tax expense due to tax reform			$ 1,381,000
Tax effect from change in tax rate		(793,000)
Cumulative undistributed foreign earnings		$ 8,345,000