CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash Flows from Operating Activities:
Net income	$ 325,944	$ 406,895
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	54,633	50,434
Impairment charges	2,346	3,795
Provision for credit losses	3,358	768
Deferred income taxes	(23,517)	4,193
Share-based compensation expense	23,543	18,512
Other	1,200	1,300
Changes in assets and liabilities:
Accounts receivable	(53,794)	(50,721)
Inventories	(49,349)	(20,412)
Other assets and liabilities	(94,729)	(55,162)
Accounts payable	(6,735)	3,812
Deferred revenue	(2,344)	(5,037)
Net cash provided by operating activities	180,556	358,377
Cash Flows from Investing Activities:
Purchases of property and equipment	(61,924)	(42,744)
Acquisition of intangible assets	(10,000)	0
Equity investment	(25,000)	0
Acquisitions of a business, net of cash acquired	0	(156,506)
Net cash used by investing activities	(96,924)	(199,250)
Cash Flows from Financing Activities:
Borrowings under revolving credit facility, net	537,500	0
Payment of senior debt	(75,000)	0
Payments of acquisition-related contingent consideration and holdbacks	(2,816)	(1,500)
Repurchases of common stock, net	(573,060)	(320,787)
Proceeds from exercises of stock options and employee stock purchase plans	18,379	27,371
Shares withheld for statutory tax withholding payments on restricted stock	(10,390)	(14,952)
Net cash used by financing activities	(105,387)	(309,868)
Net effect of changes in exchange rates on cash	(8,337)	(1,053)
Net decrease in cash and cash equivalents	(30,092)	(151,794)
Cash and cash equivalents at beginning of period	144,454	383,928
Cash and cash equivalents at end of period	114,362	232,134
Supplemental Cash Flow Information:
Cash paid for income taxes	128,325	81,923
Unpaid property and equipment, reflected in accounts payable and accrued liabilities	$ 10,340	$ 9,676