Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 307,507	$ 75,105
Short-term investments	4,124	6,862
Accounts and notes receivable, net of allowance of $1,327 and $754 as of June 30, 2018 and December 31, 2017, respectively	94,296	56,064
Contract assets, net	10,468	0
Inventory	43,967	45,465
Prepaid expenses and other current assets	26,604	21,696
Total current assets	486,966	205,192
Property and equipment, net of accumulated depreciation of $37,142 and $36,477 as of June 30, 2018 and December 31, 2017, respectively	34,503	31,172
Deferred income tax assets, net	15,813	15,755
Intangible assets, net	20,442	18,823
Goodwill	24,684	14,927
Long-term notes receivable, net of current portion	37,158	36,877
Other assets	22,831	15,366
Total assets	642,397	338,112
Current liabilities:
Accounts payable	9,213	8,592
Accrued liabilities	29,995	23,502
Current portion of deferred revenue	76,583	70,401
Customer deposits	2,970	3,673
Current portion of business acquisition contingent consideration	1,946	1,693
Other current liabilities	191	89
Total current liabilities	120,898	107,950
Deferred revenue, net of current portion	61,456	54,881
Liability for unrecognized tax benefits	1,918	1,706
Long-term deferred compensation	3,560	3,859
Business acquisition contingent consideration, net of current portion	203	1,048
Other long-term liabilities	5,520	1,224
Total liabilities	193,555	170,668
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.00001 par value; 25,000,000 shares authorized; no shares issued and outstanding as of June 30, 2018 and December 31, 2017	0	0
Common stock, $0.00001 par value; 200,000,000 shares authorized; 58,289,613 and 52,969,869 shares issued and outstanding as of June 30, 2018 and December 31, 2017, respectively	1	1
Additional paid-in capital	442,717	201,672
Treasury stock at cost, 20,220,227 shares as of June 30, 2018 and December 31, 2017	(155,947)	(155,947)
Retained earnings	163,590	123,185
Accumulated other comprehensive loss	(1,519)	(1,467)
Total stockholders’ equity	448,842	167,444
Total liabilities and stockholders’ equity	$ 642,397	$ 338,112

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).