CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 37,217	$ 27,149
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation expense	4,488	2,214
Bad debt expense	(12)	78
Stock-based compensation	24,521	21,731
Write-down of inventory	2,059	1,356
Excess tax benefit from stock-based awards	(4,595)	(488)
Deferred tax provision	18,817	17,382
Change in fair value of contingent consideration	612	882
Changes in assets and liabilities:
Accounts receivable	(7,555)	(5,084)
Inventories	(8,615)	(10,092)
Prepaid expenses and other assets	(3,923)	343
Accounts payable	3,542	(1,740)
Accrued expenses and other liabilities	11,040	632
Deferred revenue	265	(125)
Net cash provided by operating activities	77,861	54,238
Investing activities:
Purchases of marketable securities	(177,591)	(189,595)
Proceeds from the sale and maturity of marketable securities	144,670	170,195
Purchase of other investment	(149)	(750)
Purchases of property and equipment	(24,039)	(7,933)
Net cash used for investing activities	(57,109)	(28,083)
Financing activities:
Proceeds from the exercise of stock options	8,265	8,237
Excess tax benefit from stock-based awards	4,595	488
Taxes paid related to net share settlement of vesting of stock awards	(19,898)	(3,908)
Proceeds from the issuance of stock under employee stock purchase plan	769	451
Principal payments on capital lease obligation	(264)
Net cash (used for) provided by financing activities	(6,533)	5,268
Effect of exchange rate changes on cash	(1,381)	(598)
Net increase in cash and cash equivalents	12,838	30,825
Cash and cash equivalents at beginning of period	48,231	22,401
Cash and cash equivalents at end of period	61,069	53,226
Supplemental disclosure of cash flow information:
Cash paid for income taxes	735	724
Cash paid for interest on capital lease obligation	223
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	$ 3,717	$ 471