CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 2,864	$ 2,214
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,441	1,203
Investment premium amortization, net	240	243
Net loss on disposals of property and equipment	20	8
Net loss (gain) on foreign exchange translation	392	(51)
Share-based compensation expense	1,802	1,120
Excess tax benefits from share-based awards	(717)	(435)
Provision for deferred income taxes	(177)	(8)
Equity in net (income) loss of unconsolidated affiliate	(17)	38
Changes in assets and liabilities:
Receivables, net	1,569	1,463
Inventories	(1,740)	938
Prepaid expenses and other current assets	2,439	57
Other assets	(27)	4
Accounts payable	1,178	(405)
Accrued payroll and related expenses	496	86
Accrued taxes	(111)	(32)
Other accrued liabilities	(185)	128
Deferred rent	28	62
Deferred revenue	407	312
Warranty reserve	(352)	248
Net cash provided by operating activities	9,550	7,193
Cash flows from investing activities:
Purchases of held-to-maturity investments	(4,407)	(13,113)
Proceeds from maturities and redemptions of held-to-maturity investments	7,251	11,268
Purchases of property and equipment	(1,733)	(2,642)
Net cash provided by (used in) investing activities	1,111	(4,487)
Cash flows from financing activities:
Proceeds from the exercise of stock options	77	228
Tax withholdings related to net share settlements of restricted stock units	(823)	(1,825)
Excess tax benefits from share-based awards	717	435
Net cash used in financing activities	(29)	(1,162)
Effect of exchange rate changes on cash and cash equivalents	(324)	58
Net increase in cash and cash equivalents	10,308	1,602
Cash and cash equivalents at beginning of period	45,843	43,471
Cash and cash equivalents at end of period	56,151	45,073
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	148	215
Supplemental disclosure of non-cash flow information:
Change in unrealized gain (loss) on investments, net of tax	(4)	0
Transfers of equipment between inventory and property and equipment, net	439	315
Net change in capitalized share based compensation	42	47
Common stock withheld for employee taxes in connection with share-based compensation	823	1,825
Repayment of notes payable by credits from municipal agency	$ 25	$ 21