CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net income	$ 90,066	$ 37,374
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation expense	2,959	2,463
Bad debt expense (recovery)	188	(42)
Stock-based compensation	12,245	8,656
Write-down of inventory and other	897	510
Accretion on marketable securities	(363)
Deferred tax provision	(44,463)	(3,830)
Change in fair value of contingent consideration	(159)	265
Changes in assets and liabilities:
Accounts receivable	1,930	795
Inventories	(7,794)	(1,302)
Prepaid expenses and other assets	(2,131)	(915)
Accounts payable	2,684	(4,391)
Accrued expenses and other liabilities	(6,576)	(2,436)
Deferred revenue	(2,852)	(853)
Net cash provided by operating activities	46,631	36,294
Investing activities:
Purchases of marketable securities	(24,702)	(73,626)
Proceeds from the sale and maturity of marketable securities	75,782	66,622
Purchase of other investment	(1,166)	(400)
Purchases of property and equipment	(15,147)	(9,804)
Net cash provided by (used for) investing activities	34,767	(17,208)
Financing activities:
Proceeds from the exercise of stock options	5,798	3,555
Taxes paid related to net share settlement of vesting of stock awards	(67,598)	(17,805)
Principal payments on capital lease obligation		(184)
Net cash used for financing activities	(61,800)	(14,434)
Effect of exchange rate changes on cash	(1,285)	278
Net increase in cash and cash equivalents	18,313	4,930
Cash and cash equivalents at beginning of period	42,975	39,040
Cash and cash equivalents at end of period	61,288	43,970
Supplemental disclosure of cash flow information:
Cash paid for income taxes	2,956	479
Cash paid for interest on capital lease obligation		130
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment in accounts payable and accrued expenses	$ 3,196	$ 1,872