CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 22,769	$ 16,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,192	6,387
Investment premium amortization, net	898	478
Net loss on disposals of property and equipment	32	(16)
Impairment loss of intangible assets	13	0
Foreign exchange (gain) loss	(134)	938
Share-based compensation expense	8,236	7,220
Excess tax benefits from share-based awards	(1,628)	(952)
Deferred income taxes	(263)	(3,071)
Equity in net (income) loss of unconsolidated affiliate	(56)	(74)
Changes in assets and liabilities:
Receivables, net	(2,400)	(1,537)
Inventories	159	(6,660)
Prepaid expenses and other current assets	(2,369)	(1,378)
Other assets	(485)	(76)
Accounts payable	155	920
Accrued payroll and related expenses	(4,189)	3,393
Accrued taxes	(4,539)	24
Other liabilities	(5,372)	5,760
Deferred revenue	(488)	(559)
Warranty reserve	(62)	1,039
Net cash provided by operating activities	15,469	27,836
Cash flows from investing activities:
Purchases of available-for-sale investments	(1,726)	0
Purchases of held-to-maturity investments	(41,064)	(23,478)
Proceeds from maturities and redemptions of available-for-sale investments	0	6,498
Proceeds from maturities and redemptions of held-to-maturity investments	19,212	20,725
Purchases of property and equipment	(4,405)	(4,964)
Proceeds from disposals of property and equipment	0	25
Acquisitions, net of cash acquired	(1,131)	(721)
Net cash provided by (used in) investing activities	(29,114)	(1,915)
Cash flows from financing activities:
Proceeds from the exercise of stock options	0	24
Tax withholdings related to net share settlements of restricted stock units	(5,237)	(3,013)
Excess tax benefits from share-based awards	1,628	952
Proceeds from the exercise of warrants	12	72
Dividends paid	(7,494)	(6,752)
Net cash used in financing activities	(11,091)	(8,717)
Effect of exchange rate changes on cash and cash equivalents	123	(1,023)
Net increase (decrease) in cash and cash equivalents	(24,613)	16,181
Cash and cash equivalents at beginning of period	107,015	73,589
Cash and cash equivalents at end of period	82,402	89,770
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	17,623	11,136
Supplemental disclosure of non-cash flow information:
Change in unrealized gain (loss) on investments, net of tax	(9)	(17)
Transfers of equipment between inventory and property and equipment, net	902	1,552
Net change in capitalized share-based compensation	60	(30)
Common stock withheld for employee taxes in connection with share-based compensation	5,237	3,013
Repayment of notes payable by credits from municipal agency	76	76
Settlement of preexisting business relationship in connection with acquisition	0	931
Installment payment obligation related to acquisition	$ 0	$ 2,336