Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 22,709	$ 15,136
Adjustments to reconcile net income to cash provided by operating activities, net of the effects of acquisitions:
Depreciation and amortization	9,753	9,512
Loss on disposal of fixed assets	0	37
Deal related compensation expense and accretion charges	76	73
Share-based compensation expense associated with equity awards	7,797	6,742
Net change in fair value of contingent and contractual liabilities	(9)	(278)
Deferred income taxes	1,760	1,823
Other losses (gains)	85	(7)
Changes in assets and liabilities
Accounts receivable	10,684	18,271
Inventories	(2,871)	(4,946)
Prepaid expenses and other assets	(3,367)	(340)
Accounts payable	(1,226)	(1,511)
Accrued compensation and other expenses	672	(5,881)
Income taxes payable	(791)	(114)
Deferred revenue	(16,282)	(11,416)
Net cash provided by operating activities	28,990	27,101
Cash flows from investing activities:
Purchase of marketable securities	(57,790)	(43,750)
Proceeds from maturity of marketable securities	36,204	33,383
Purchase of fixed assets	(4,016)	(6,355)
Purchase of intangible assets	(92)	(153)
Decrease in deposits	101	38
Net cash used in investing activities	(25,593)	(16,837)
Cash flows from financing activities:
Issuance of common stock under stock plans	67	315
Payment of contingent consideration	0	(841)
Treasury stock repurchases	(30,894)	(16,349)
Excess tax benefit from share-based compensation awards	4,033	1,733
Net cash used in financing activities	(26,794)	(15,142)
Effect of exchange rate changes on cash and cash equivalents	307	(135)
Net decrease in cash and cash equivalents	(23,090)	(5,013)
Cash and cash equivalents, beginning of period	102,076	99,930
Cash and cash equivalents, end of period	78,986	94,917
Supplemental disclosures:
Cash paid for income taxes	15,587	7,922
Non-cash transactions:
Transfers of inventory to fixed assets	940	1,781
Additions to property, plant and equipment included in accounts payable	120	(64)
Gross decrease in contractual liability relating to fair value adjustment	(49)	(98)
Gross increase (decrease) in contingent consideration liability relating to fair value adjustment	40	(180)
Issuance of common stock under employee stock plans	$ 2,760	$ 2,230