CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	3 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income	$ 5,693	$ 6,801
Adjustments to reconcile net income to net cash provided by (used for) operating activities:
Depreciation and amortization	1,541	1,189
Provisions for contracts, inventory and accounts receivable reserves	33	165
Amortization of bond premium	556	595
Deferred income taxes	466	1,010
Mark-to-market of foreign currency put option contract		(1,142)
Stock compensation expense	607	1,024
Changes in assets and liabilities:
Accounts receivable	9,671	(2,029)
Unbilled costs and fees	(4,121)	844
Inventories	(1,779)	(1,948)
Prepaid expenses and other assets	(2,482)	631
Accounts payable	(483)	(1,895)
Accrued income taxes	553	(3,915)
Customer deposits	8,848	(2,510)
Deferred revenue	3,446	(6,822)
Accrued expenses and other liabilities	(8,526)	(5,717)
Net cash provided by (used for) operating activities	14,023	(13,719)
Cash flows from investing activities:
Purchases of short-term investments	(90,577)	(10,571)
Proceeds from sales and maturities of short-term investments	52,069	78,569
Purchases of property and equipment	(2,103)	(1,230)
Net cash (used for) provided by investing activities	(40,611)	66,768
Cash flows from financing activities:
Decrease in restricted cash and investments	15,385
Proceeds from exercise of stock options	2,833	220
Repurchase of shares of common stock	(22)
Repayment of leasehold financing	(330)	(323)
Payment of common stock dividend	(2,760)	(2,707)
Reduction of income taxes paid due to the tax benefit from employee stock option expense	262	255
Net cash provided by (used for) financing activities	15,368	(2,555)
Net (decrease) increase in cash and cash equivalents	(11,220)	50,494
Cash and cash equivalents at beginning of period	60,144	34,912
Cash and cash equivalents at end of period	$ 48,924	$ 85,406