CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income		$ 67,642	$ 63,908
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		13,499	11,865
Operating lease cost		30,213	29,679
Inventory donations		8,821	5
Provision for doubtful accounts, net		6,507	988
Share-based compensation		5,942	7,401
Other non-cash items		2,029	(1,627)
Changes in operating assets and liabilities:
Accounts receivable		(62,146)	(73,000)
Inventories		11,240	(9,955)
Prepaid expenses and other assets		1,002	(912)
Accounts payable, accrued expenses and other liabilities		(15,316)	26,548
Operating lease liabilities		(29,166)	(34,732)
Cash provided by operating activities		40,267	20,168
Cash flows from investing activities:
Purchases of property, equipment, and software		(24,328)	(18,722)
Proceeds from disposal of property and equipment		434	260
Other		(116)	0
Cash used in investing activities		(24,010)	(18,462)
Cash flows from financing activities:
Proceeds from bank borrowings		150,000	95,000
Repayments of bank borrowings		(80,000)	0
Dividends—Series A convertible preferred stock	[1]	0	(2,985)
Repurchases of common stock		(39,159)	(108,475)
Other		(1,964)	(1,635)
Cash provided by (used in) financing activities		28,877	(18,095)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		(2,360)	410
Net change in cash, cash equivalents, and restricted cash		42,774	(15,979)
Cash, cash equivalents, and restricted cash—beginning of period		112,045	127,530
Cash, cash equivalents, and restricted cash—end of period		$ 154,819	$ 111,551

[1] For the six months ended June 30, 2019, represents $3.0 million paid to induce conversion of Series A Convertible Preferred Stock to common stock.