Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 65,922	$ 46,874
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,829	6,994
Loss on disposal and sale of property and equipment, net	3	15
Amortization of premium on available-for-sale securities	1,121	216
(Gain) loss on deferred compensation plan investments	178	(2,555)
Deferred taxes, net	3,400	(20)
Stock-based compensation expense	39,606	38,719
Changes in operating assets and liabilities:
Accounts receivable	(2,428)	(176)
Inventories	(24,580)	(7,205)
Other assets	(10,001)	(42)
Accounts payable	15,489	2,153
Accrued compensation and related benefits	6,773	4,124
Income tax liabilities	(61)	(6,627)
Other accrued liabilities	6,498	423
Net cash provided by operating activities	110,749	82,893
Cash flows from investing activities:
Purchases of property and equipment	(24,536)	(77,638)
Acquisition of in-place leases	0	(981)
Purchases of short-term investments	(189,637)	(21,546)
Proceeds from maturities and sales of short-term investments	118,701	57,999
Proceeds from sales of long-term investments	125	75
Proceeds from sales of property and equipment	1	1,456
Contributions to deferred compensation plan, net	(775)	(1,435)
Net cash used in investing activities	(96,121)	(42,070)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(4,061)	(3)
Proceeds from common stock issued under the employee equity incentive plan	14,110	12,471
Proceeds from common stock issued under the employee stock purchase plan	1,892	1,627
Dividends and dividend equivalents paid	(42,267)	(30,784)
Net cash used in financing activities	(30,326)	(16,689)
Effect of change in exchange rates	(777)	175
Net increase (decrease) in cash, cash equivalents and restricted cash	(16,475)	24,309
Cash, cash equivalents and restricted cash, beginning of period	173,076	172,818
Cash, cash equivalents and restricted cash, end of period	156,601	197,127
Supplemental disclosures for cash flow information:
Cash paid for taxes	633	7,168
Non-cash investing and financing activities:
Liability accrued for property and equipment purchases	7,258	3,028
Liability accrued for dividends and dividend equivalents	$ 25,044	$ 19,749