CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ 27,149	$ 14,814
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,214	1,796
Bad debt expense	78	43
Stock-based compensation	21,731	12,696
Write-down of inventory	1,356	1,135
Excess tax benefit from stock-based awards	(488)
Deferred tax provision	17,382	675
Change in fair value of contingent consideration	882	365
Changes in assets and liabilities:
Accounts receivable	(5,084)	(4,320)
Inventories	(10,092)	(3,582)
Prepaid expenses and other assets	343	(180)
Accounts payable	(1,740)	368
Accrued expenses and other liabilities	632	(639)
Deferred revenue	(125)	1,856
Net cash provided by operating activities	54,238	25,027
Investing activities:
Purchases of marketable securities	(189,595)	(72,411)
Proceeds from the sale and maturity of marketable securities	170,195	57,890
Acquisition of ECP and AIS, net of cash assumed		(15,697)
Purchase of other investment	(750)	(1,250)
Purchases of property and equipment	(7,933)	(2,232)
Net cash used for investing activities	(28,083)	(33,700)
Financing activities:
Proceeds from the exercise of stock options	8,237	8,624
Excess tax benefit from stock-based awards	488
Taxes paid related to net share settlement of vesting of stock awards	(3,908)	(1,013)
Proceeds from the issuance of stock under employee stock purchase plan	451	397
Net cash provided by financing activities	5,268	8,008
Effect of exchange rate changes on cash	(598)	(773)
Net increase (decrease) in cash and cash equivalents	30,825	(1,438)
Cash and cash equivalents at beginning of period	22,401	20,916
Cash and cash equivalents at end of period	53,226	19,478
Supplemental disclosure of cash flow information:
Cash paid for income taxes	724	1,090
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	$ 471	$ 501