Carrying Amounts and Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets
Cash and cash equivalents	$ 45,702	$ 57,743
Accounts receivable	275	368
Refundable deposits	208	199
Marketable securities - noncurrent (Note 8)	10,000
Financial liabilities
Accounts payable	70	64
Accrued expenses	1,516	1,280
Lease liabilities - current and noncurrent	98	592
Carrying Amount
Financial assets
Cash and cash equivalents	45,702	57,743
Accounts receivable	275	368
Restricted cash	300	531
Refundable deposits	208	199
Marketable securities - noncurrent (Note 8)	10,000
Financial liabilities
Accounts payable	70	64
Accrued expenses	1,516	1,280
Lease liabilities - current and noncurrent	98	592
Estimated Fair Value
Financial assets
Cash and cash equivalents	45,702	57,743
Accounts receivable	275	368
Restricted cash	300	531
Refundable deposits	208	199
Marketable securities - noncurrent (Note 8)	10,000
Financial liabilities
Accounts payable	70	64
Accrued expenses	1,516	1,280
Lease liabilities - current and noncurrent	$ 98	$ 592

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).

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Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Carrying value of amounts transferred to third parties for security purposes that are expected to be returned or applied towards payment after one year or beyond the operating cycle, if longer.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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