Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net income	$ 168,669	$ 171,211
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,271	14,427
Bad debt (recoveries) expense	(192)	241
Stock-based compensation	33,719	37,019
Write-down of inventory and other	5,078	3,984
Accretion on marketable securities	1,183	(2,678)
Change in fair value of other investments	(43,107)	(17,407)
Deferred tax provision	22,920	30,551
Change in fair value of contingent consideration	3,016	865
Other non-cash operating activities	3,194	3,167
Changes in assets and liabilities:
Accounts receivable	(6,925)	(10,333)
Inventories	6,596	(13,261)
Prepaid expenses and other assets	(7,061)	(4,250)
Accounts payable	(8,147)	841
Accrued expenses and other liabilities	(10,000)	11,193
Deferred revenue	1,889	2,757
Net cash provided by operating activities	188,103	228,327
Investing activities:
Purchases of marketable securities	(487,753)	(491,513)
Proceeds from the sale and maturity of marketable securities and other	338,331	410,456
Purchases of other investments and intangible assets	(26,104)	(20,899)
Acquisition of Breethe Inc., net of cash acquired	(52,183)
Proceeds from sales of Shockwave Medical investment	67,882
Purchases of property and equipment	(27,274)	(33,460)
Net cash used for investing activities	(187,101)	(135,416)
Financing activities:
Proceeds from the exercise of stock options	7,076	3,165
Taxes paid related to net share settlement upon vesting of stock awards	(11,176)	(41,607)
Repurchase of common stock	(11,310)	(59,876)
Proceeds from the issuance of stock under employee stock purchase plan	1,978	2,368
Net cash used for financing activities	(13,432)	(95,950)
Effect of exchange rate changes on cash and cash equivalents	1,107	(12)
Net decrease in cash and cash equivalents	(11,323)	(3,051)
Cash and cash equivalents at beginning of period	192,341	121,021
Cash and cash equivalents at end of period	181,018	117,970
Supplemental disclosure of cash flow information:
Cash paid for income taxes	34,024	7,479
Supplemental disclosure of non-cash activities:
Contingent consideration related to the acquisition of Breethe	13,300
Property and equipment in accounts payable and accrued expenses	640	3,314
Right-of-use assets obtained in exchange for lease liabilities	$ 1,378	$ 14,596