CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 10,115	$ 7,225
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,166	3,584
Investment premium amortization, net	301	322
Net loss on disposals of property and equipment	2	6
Foreign exchange (gain) loss	564	(406)
Share-based compensation expense	4,527	4,102
Excess tax benefits from share-based awards	(859)	(1,729)
Deferred income taxes	(1,517)	(428)
Equity in net (income) loss of unconsolidated affiliate	32	(16)
Changes in assets and liabilities:
Receivables, net	(7,214)	4,962
Inventories	(3,223)	(1,174)
Prepaid expenses and other current assets	(815)	(699)
Other assets	(60)	13
Accounts payable	4,053	(1,126)
Accrued payroll and related expenses	4,148	(769)
Accrued taxes	(214)	(17)
Other accrued liabilities	2,483	(460)
Deferred rent	0	22
Deferred revenue	(441)	535
Warranty reserve	317	229
Net cash provided by operating activities	16,365	14,176
Cash flows from investing activities:
Purchases of held-to-maturity investments	(13,650)	(8,036)
Proceeds from maturities and redemptions of available-for-sale investments	498	525
Proceeds from maturities and redemptions of held-to-maturity investments	18,729	15,113
Purchases of property and equipment	(3,904)	(2,761)
Proceeds from disposals of property and equipment	0	9
Net cash provided by investing activities	1,673	4,850
Cash flows from financing activities:
Proceeds from the exercise of stock options	4	26
Tax withholdings related to net share settlements of restricted stock units	(2,884)	(4,591)
Excess tax benefits from share-based awards	859	1,729
Proceeds from the exercise of warrants	60	0
Dividends paid	(4,498)	0
Net cash used in financing activities	(6,459)	(2,836)
Effect of exchange rate changes on cash and cash equivalents	(574)	346
Net increase in cash and cash equivalents	11,005	16,536
Cash and cash equivalents at beginning of period	73,589	54,910
Cash and cash equivalents at end of period	84,594	71,446
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	7,138	4,006
Supplemental disclosure of non-cash flow information:
Change in unrealized gain (loss) on investments, net of tax	(13)	(8)
Transfers of equipment between inventory and property and equipment, net	1,223	618
Net change in capitalized share-based compensation	9	26
Common stock withheld for employee taxes in connection with share-based compensation	2,884	4,591
Repayment of notes payable by credits from municipal agency	$ 50	$ 50