CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating activities:
Net income	$ 16,594	$ 2,130
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,352	1,196
Bad debt (recovery) expense	(18)	27
Stock-based compensation	15,592	8,314
Write-down of inventory	952	559
Excess tax benefit from stock-based awards	(383)
Deferred tax provision	10,803	450
Change in fair value of contingent consideration	307	219
Changes in assets and liabilities:
Accounts receivable	(5,214)	1,108
Inventories	(6,855)	(653)
Prepaid expenses and other assets	456	(139)
Accounts payable	(1,817)	(581)
Accrued expenses and other long-term liabilities	(2,674)	(3,732)
Deferred revenue	(239)	1,004
Net cash provided by operating activities	28,856	9,902
Investing activities:
Purchases of marketable securities	(99,002)	(44,920)
Proceeds from the sale and maturity of marketable securities	101,453	47,890
Acquisition of ECP and AIS, net of cash assumed		(15,697)
Purchase of other investment	(750)	(750)
Purchases of property and equipment	(3,419)	(1,496)
Net cash used for investing activities	(1,718)	(14,973)
Financing activities:
Proceeds from the exercise of stock options	7,971	2,560
Excess tax benefit from stock-based awards	383
Taxes paid related to net share settlement of vesting of stock awards	(3,810)	(1,013)
Proceeds from the issuance of stock under employee stock purchase plan	451	397
Net cash provided by financing activities	4,995	1,944
Effect of exchange rate changes on cash	(113)	(306)
Net increase (decrease) in cash and cash equivalents	32,020	(3,433)
Cash and cash equivalents at beginning of period	22,401	20,916
Cash and cash equivalents at end of period	54,421	17,483
Supplemental disclosure of cash flow information:
Cash paid for income taxes	576	299
Supplemental disclosure of non-cash investing and financing activities:
Contingent consideration related to acquisition of ECP		6,000
Property and equipment in accounts payable and accrued expenses	$ 396	$ 577