CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net income	$ 21,785	$ 16,594
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation expense	2,958	1,352
Bad debt expense	(13)	(18)
Stock-based compensation	18,047	15,592
Write-down of inventory	1,354	952
Excess tax benefit from stock-based awards	(3,631)	(383)
Deferred tax provision	9,777	10,803
Change in fair value of contingent consideration	186	307
Changes in assets and liabilities:
Accounts receivable	(3,807)	(5,214)
Inventories	(6,284)	(6,855)
Prepaid expenses and other assets	(2,029)	456
Accounts payable	1,906	(1,817)
Accrued expenses and other liabilities	3,157	(2,674)
Deferred revenue	330	(239)
Net cash provided by operating activities	43,736	28,856
Investing activities:
Purchases of marketable securities	(134,235)	(99,002)
Proceeds from the sale and maturity of marketable securities	116,685	101,453
Purchase of other investment		(750)
Purchases of property and equipment	(10,453)	(3,419)
Net cash used for investing activities	(28,003)	(1,718)
Financing activities:
Proceeds from the exercise of stock options	5,764	7,971
Excess tax benefit from stock-based awards	3,631	383
Taxes paid related to net share settlement of vesting of stock awards	(19,608)	(3,810)
Proceeds from the issuance of stock under employee stock purchase plan	769	451
Principal payments on capital lease obligation	(83)
Net cash (used for) provided by financing activities	(9,527)	4,995
Effect of exchange rate changes on cash	272	(113)
Net increase in cash and cash equivalents	6,478	32,020
Cash and cash equivalents at beginning of period	48,231	22,401
Cash and cash equivalents at end of period	54,709	54,421
Supplemental disclosure of cash flow information:
Cash paid for income taxes	560	576
Cash paid for interest on capital lease obligation	89
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment under capital lease obligation	16,784
Property and equipment in accounts payable and accrued expenses	$ 3,810	$ 396