Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net income	$ 44,588	$ 88,923
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,480	4,365
Bad debt expense	(277)	(21)
Stock-based compensation	9,298	13,121
Write-down of inventory and other	1,717	1,259
Accretion on marketable securities	94	(1,306)
Change in fair value of other investments	(23,823)	(39,654)
Deferred tax provision	12,946	10,776
Change in fair value of contingent consideration	801	356
Other non-cash operating activities	970	1,003
Changes in assets and liabilities:
Accounts receivable	3,014	4,801
Inventories	(211)	(7,239)
Prepaid expenses and other assets	485	(3,417)
Accounts payable	(4,458)	(1,463)
Accrued expenses and other liabilities	(19,584)	(6,643)
Deferred revenue	719	(233)
Net cash provided by operating activities	31,759	64,628
Investing activities:
Purchases of marketable securities	(62,066)	(124,067)
Proceeds from the sale and maturity of marketable securities and other	139,813	93,180
Purchases of other investments and intangible assets	(2,000)	(2,800)
Acquisition of Breethe Inc., net of cash acquired	(51,947)
Purchases of property and equipment	(10,044)	(12,250)
Net cash provided by (used for) investing activities	13,756	(45,937)
Financing activities:
Proceeds from the exercise of stock options	1,010	1,260
Taxes paid related to net share settlement upon vesting of stock awards	(9,857)	(40,536)
Repurchase of common stock	(11,310)
Net cash used for financing activities	(20,157)	(39,276)
Effect of exchange rate changes on cash	(2,872)	612
Net increase (decrease) in cash and cash equivalents	22,486	(19,973)
Cash and cash equivalents at beginning of period	192,341	121,021
Cash and cash equivalents at end of period	214,827	101,048
Supplemental disclosure of cash flow information:
Cash paid for income taxes	2,831	2,584
Supplemental disclosure of non-cash activities:
Contingent consideration related to the acquisition of Breethe, Inc.	13,900
Property and equipment in accounts payable and accrued expenses	2,044	3,619
Right-of-use assets obtained in exchange for lease liabilities	$ 804	$ 14,139