Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	3 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income	$ 2,214	$ 3,580
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,203	1,052
Investment premium amortization, net	243	95
Net loss on disposals of property and equipment	8	4
Net (gain) loss on foreign exchange translation	(51)	300
Share-based compensation expense	1,120	1,134
Excess tax benefits from share-based awards	(435)	(409)
Provision for deferred income taxes	(8)	118
Equity in net loss of unconsolidated affiliate	38	0
Changes in assets and liabilities:
Receivables, net	1,463	(192)
Inventories	938	1,669
Prepaid expenses and other current assets	57	403
Other assets	4	(14)
Accounts payable	(405)	(4,659)
Accrued payroll and related expenses	86	(379)
Accrued taxes	(32)	1,611
Other accrued liabilities	128	(227)
Deferred rent	62	71
Deferred revenue	312	98
Warranty reserve	248	(329)
Net cash provided by operating activities	7,193	3,926
Cash flows from investing activities:
Purchases of held-to-maturity investments	(13,113)	(14,680)
Proceeds from maturities and redemptions of held-to-maturity investments	11,268	21,218
Purchases of property and equipment	(2,642)	(815)
Net cash (used in) provided by investing activities	(4,487)	5,723
Cash flows from financing activities:
Proceeds from the exercise of stock options	228	324
Tax withholdings related to net share settlements of restricted stock units	(1,825)	(1,562)
Excess tax benefits from share-based awards	435	409
Net cash used in financing activities	(1,162)	(829)
Effect of exchange rate changes on cash and cash equivalents	58	(329)
Net increase in cash and cash equivalents	1,602	8,491
Cash and cash equivalents at beginning of period	43,471	27,857
Cash and cash equivalents at end of period	45,073	36,348
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	215	168
Supplemental disclosure of non-cash flow information:
Transfers of equipment between inventory and property and equipment, net	315	260
Net change in capitalized share-based compensation	47	15
Common stock withheld for employee taxes in connection with share-based compensation	1,825	1,562
Repayment of notes payable by credits from municipal agency	$ 21	$ 0