Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 223,642	$ 349,462
Short-term investments	105,312	0
Accounts and notes receivable, net of allowance of $2,355 and $1,882 as of March 31, 2019 and December 31, 2018, respectively	149,096	130,579
Contract assets, net	17,945	13,960
Inventory	37,587	33,763
Prepaid expenses and other current assets	33,340	30,391
Total current assets	566,922	558,155
Property and equipment, net of accumulated depreciation of $41,707 and $39,885 as of March 31, 2019 and December 31, 2018, respectively	41,347	37,893
Deferred income tax assets, net	18,770	19,347
Intangible assets, net	15,067	15,935
Goodwill	25,017	24,981
Long-term notes receivable, net of current portion	36,316	40,230
Other assets	35,756	22,999
Total assets	739,195	719,540
Current liabilities:
Accounts payable	9,865	15,164
Accrued liabilities	36,348	41,092
Contract with customer, liability, current	110,063	107,016
Other current liabilities	3,914	37
Total current liabilities	163,794	166,011
Deferred revenue, net of current portion	74,784	74,417
Liability for unrecognized tax benefits	3,156	2,849
Long-term deferred compensation	3,675	3,235
Other long-term liabilities	13,247	5,704
Total liabilities	258,656	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 March 31, 2019 and December 31, 2018	0	0
Common stock, $0.00001 par value; 200,000,000 shares authorized; 59,109,286 and 58,810,637 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	460,146	453,400
Treasury stock at cost, 20,220,227 shares as of March 31, 2019 and December 31, 2018	(155,947)	(155,947)
Retained earnings	177,802	171,383
Accumulated other comprehensive loss	(1,463)	(1,513)
Total stockholders’ equity	480,539	467,324
Total liabilities and stockholders’ equity	739,195	719,540
Current portion of deferred revenue
Current liabilities:
Contract with customer, liability, current	110,063	107,016
Customer deposits
Current liabilities:
Contract with customer, liability, current	$ 3,604	$ 2,702

The aggregate of amounts due from customers or clients, within one year of the balance sheet date (or one operating cycle, if longer), for goods or services that have been delivered or sold in the normal course of business and an amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date within one year of the balance sheet, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection and net of any write-downs taken for collection uncertainty on the part of the holder, respectively.

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- Definition

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).