Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 202,551	$ 349,462
Short-term investments	108,913	0
Accounts and notes receivable, net of allowance of $1,983 and $1,882 as of September 30, 2019 and December 31, 2018, respectively	149,013	130,579
Contract assets, net	33,602	13,960
Inventory	40,666	33,763
Prepaid expenses and other current assets	41,277	30,391
Total current assets	576,022	558,155
Property and equipment, net of accumulated depreciation of $38,470 and $39,885 as of September 30, 2019 and December 31, 2018, respectively	42,592	37,893
Deferred income tax assets, net	23,290	19,347
Intangible assets, net	13,528	15,935
Goodwill	24,876	24,981
Long-term investments	41,391	0
Long-term notes receivable, net of current portion	33,463	40,230
Other assets	37,142	22,999
Total assets	792,304	719,540
Current liabilities:
Accounts payable	14,638	15,164
Accrued liabilities	35,745	41,092
Contract with customer, liability, current	127,160	107,016
Other current liabilities	3,997	37
Total current liabilities	183,834	166,011
Deferred revenue, net of current portion	82,149	74,417
Liability for unrecognized tax benefits	3,443	2,849
Long-term deferred compensation	3,694	3,235
Other long-term liabilities	11,537	5,704
Total liabilities	284,657	252,216
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, $0.00001 par value; 25,000,000 shares authorized; no shares issued and outstanding as of September 30, 2019 and December 31, 2018	0	0
Common stock, $0.00001 par value; 200,000,000 shares authorized; 59,320,793 and 58,810,637 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	480,747	453,400
Treasury stock at cost, 20,220,227 shares as of September 30, 2019 and December 31, 2018	(155,947)	(155,947)
Retained earnings	184,644	171,383
Accumulated other comprehensive loss	(1,798)	(1,513)
Total stockholders’ equity	507,647	467,324
Total liabilities and stockholders’ equity	792,304	719,540
Current portion of deferred revenue
Current liabilities:
Contract with customer, liability, current	127,160	107,016
Customer deposits
Current liabilities:
Contract with customer, liability, current	$ 2,294	$ 2,702