Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 35,756	$ 26,181
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,328	3,255
(Gain) loss on disposal and sale of property and equipment, net	(1)	14
Amortization of premium on available-for-sale securities	494	121
(Gain) loss on deferred compensation plan investments	3,750	(1,935)
Deferred taxes, net	3,412	(33)
Stock-based compensation expense	18,562	16,010
Changes in operating assets and liabilities:
Accounts receivable	(1,635)	(3,676)
Inventories	(3,994)	(6,171)
Other assets	(10,061)	(1,576)
Accounts payable	7,185	4,778
Accrued compensation and related benefits	(7,374)	4
Income tax liabilities	34	(1,491)
Other accrued liabilities	963	3,355
Net cash provided by operating activities	51,419	38,836
Cash flows from investing activities:
Purchases of property and equipment	(9,952)	(58,376)
Acquisition of in-place leases	0	(981)
Purchases of short-term investments	(101,566)	0
Proceeds from maturities and sales of short-term investments	47,397	28,076
Proceeds from sales of long-term investments	100	0
Proceeds from sales of property and equipment	1	1,456
Contributions to deferred compensation plan, net	(438)	(956)
Net cash used in investing activities	(64,458)	(30,781)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(279)	(10)
Proceeds from common stock issued under the employee equity incentive plan	11,758	10,383
Proceeds from common stock issued under the employee stock purchase plan	1,892	1,627
Dividends and dividend equivalents paid	(17,427)	(12,761)
Net cash used in financing activities	(4,056)	(761)
Effect of change in exchange rates	(985)	1,770
Net increase (decrease) in cash, cash equivalents and restricted cash	(18,080)	9,064
Cash, cash equivalents and restricted cash, beginning of period	173,076	172,818
Cash, cash equivalents and restricted cash, end of period	154,996	181,882
Supplemental disclosures for cash flow information:
Cash paid for taxes	279	393
Non-cash investing and financing activities:
Liability accrued for property and equipment purchases	10,909	958
Liability accrued for dividends and dividend equivalents	$ 23,725	$ 18,534