Organization and Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2016
Organization and Summary of Significant Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies (a) The Company and Basis of Presentation AeroCentury Corp. ("the Company"), a Delaware corporation incorporated in 1997, typically acquires used regional aircraft and engines for lease to foreign and domestic regional carriers. The condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three-month and six-month periods ended June 30, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016. For further information, refer to the financial statements and footnotes thereto included in the Company's annual report on Form 10-K for the year ended December 31, 2015. (b) Use of Estimates The Company's financial statements have been prepared in accordance with GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable for making judgments that are not readily apparent from other sources. The most significant estimates with regard to these financial statements are the residual values and useful lives of the assets, the amount and timing of cash flows associated with each asset that are used to evaluate whether assets are impaired, accrued maintenance costs, accounting for income taxes, and the amounts recorded as allowances for doubtful accounts. (c) Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs, to the extent possible. The fair value hierarchy under GAAP is based on three levels of inputs. Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis The carrying amount of the Company's money market funds included in cash and cash equivalents was $947,400 and $1,946,600 at June 30, 2016 and December 31, 2015, respectively. The fair value of the Company's money market funds would be categorized as Level 1 under the GAAP fair value hierarchy. As of June 30, 2016 and December 31, 2015, there were no liabilities that were required to be measured and recorded at fair value on a recurring basis. Assets Measured and Recorded at Fair Value on a Nonrecurring Basis The Company determines fair value of long-lived assets held and used, such as aircraft and aircraft engines held for lease and assets held for sale, by reference to independent appraisals, quoted market prices (e.g., offers to purchase) and other factors. An impairment charge is recorded when the Company believes that the carrying value of an asset will not be recovered through future net cash flows and that the asset's carrying value exceeds its fair value. Assets held for lease The Company recorded impairment charges of $0 and $147,500 on its aircraft held for lease during the three months and six months ended June 30, 2016 and 2015, respectively. Assets held for sale The Company recorded a $246,200 impairment charge on an engine held for sale during the three months ended June 30, 2016, resulting in a carrying value of $295,000. The fair value of this asset would be categorized as Level 3 under the GAAP fair value hierarchy. No such impairment charges were recorded during the three months ended June 30, 2015. During the six months ended June 30, 2016, the Company also recorded a $75,000 impairment charge on two of its aircraft held for sale. The aircraft were sold during the second quarter. Fair Value of Other Financial Instruments The Company's financial instruments, other than cash and cash equivalents, consist principally of finance leases receivable and amounts borrowed under its credit facility (the "Credit Facility"). The fair value of accounts receivable, finance leases receivable, accounts payable and the Company's maintenance reserves and accrued maintenance costs approximates the carrying value of these financial instruments. Borrowings under the Company's Credit Facility bear floating rates of interest that reset periodically to a market benchmark rate plus a credit margin. The Company believes the effective interest rate under the Credit Facility approximates current market rates for such indebtedness at the balance sheet date, and therefore that the outstanding principal and accrued interest of $78,809,300 and $110,435,600 at June 30, 2016 and December 31, 2015, respectively, approximate its fair values on such dates. The fair value of the Company's outstanding balance of its Credit Facility would be categorized as Level 3 under the GAAP fair value hierarchy. (d) Finance Leases The Company has five aircraft finance leases that contain lessee purchase options at prices substantially below the assets' estimated residual values at the exercise date for the option. Consequently, the Company considers the purchase options to be bargain purchase options and has classified the leases as sales-type finance leases for financial accounting purposes. The Company reports the discounted present value of (i) future minimum lease payments (including the bargain purchase option) and (ii) any residual value not subject to a bargain purchase option as a finance lease receivable on its balance sheet and accrues interest on the balance of the finance lease receivable based on the interest rate inherent in the applicable lease over the term of the lease. For sales-type finance leases, the Company recognizes the difference between the net book value of the aircraft and the net investment in sales-type finance leases, less any initial direct costs and lease incentives, as a gain or loss. The Company recognized interest earned on finance leases in the amount of $187,000 and $91,400 in the quarters ended June 30, 2016 and 2015, respectively and $372,100 and $91,400 in the six months ended June 30, 2016 and 2015, respectively. (e) Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-13, Financial Instruments -- Credit Losses (Topic 326) ("ASU 2016-13"), which will modify accounting for credit losses on most financial assets measured at amortized cost, including net investment in leases. Unlike current accounting, which delays credit loss recognition until a probable loss is incurred, the new model will use a current expected credit loss ("CECL") model that will estimate future credit losses over the entire term of the financial instrument. As such, it is generally expected that adoption of the CECL model will result in earlier recognition of credit losses than current GAAP. The Company will be required to adopt ASU 2016-13 for its yearly and interim periods beginning after December 15, 2019, although adoption in the preceding year and periods is permitted. The Company has not yet estimated the impact of adoption of this standard on its financial statements.

1. Organization and Summary of Significant Accounting Policies

(a) The Company and Basis of Presentation

AeroCentury Corp. ("the Company"), a Delaware corporation incorporated in 1997, typically acquires used regional aircraft and engines for lease to foreign and domestic regional carriers.

The condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three-month and six-month periods ended June 30, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016.

For further information, refer to the financial statements and footnotes thereto included in the Company's annual report on Form 10-K for the year ended December 31, 2015.

(b) Use of Estimates

The Company's financial statements have been prepared in accordance with GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable for making judgments that are not readily apparent from other sources.

The most significant estimates with regard to these financial statements are the residual values and useful lives of the assets, the amount and timing of cash flows associated with each asset that are used to evaluate whether assets are impaired, accrued maintenance costs, accounting for income taxes, and the amounts recorded as allowances for doubtful accounts.

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs, to the extent possible. The fair value hierarchy under GAAP is based on three levels of inputs.

Level 1 - Quoted prices in active markets for identical assets or liabilities.

Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis

The carrying amount of the Company's money market funds included in cash and cash equivalents was $947,400 and $1,946,600 at June 30, 2016 and December 31, 2015, respectively. The fair value of the Company's money market funds would be categorized as Level 1 under the GAAP fair value hierarchy.

As of June 30, 2016 and December 31, 2015, there were no liabilities that were required to be measured and recorded at fair value on a recurring basis.

Assets Measured and Recorded at Fair Value on a Nonrecurring Basis

The Company determines fair value of long-lived assets held and used, such as aircraft and aircraft engines held for lease and assets held for sale, by reference to independent appraisals, quoted market prices (e.g., offers to purchase) and other factors. An impairment charge is recorded when the Company believes that the carrying value of an asset will not be recovered through future net cash flows and that the asset's carrying value exceeds its fair value.

Assets held for lease

The Company recorded impairment charges of $0 and $147,500 on its aircraft held for lease during the three months and six months ended June 30, 2016 and 2015, respectively.

Assets held for sale

The Company recorded a $246,200 impairment charge on an engine held for sale during the three months ended June 30, 2016, resulting in a carrying value of $295,000. The fair value of this asset would be categorized as Level 3 under the GAAP fair value hierarchy. No such impairment charges were recorded during the three months ended June 30, 2015. During the six months ended June 30, 2016, the Company also recorded a $75,000 impairment charge on two of its aircraft held for sale. The aircraft were sold during the second quarter.

Fair Value of Other Financial Instruments

The Company's financial instruments, other than cash and cash equivalents, consist principally of finance leases receivable and amounts borrowed under its credit facility (the "Credit Facility"). The fair value of accounts receivable, finance leases receivable, accounts payable and the Company's maintenance reserves and accrued maintenance costs approximates the carrying value of these financial instruments.

Borrowings under the Company's Credit Facility bear floating rates of interest that reset periodically to a market benchmark rate plus a credit margin. The Company believes the effective interest rate under the Credit Facility approximates current market rates for such indebtedness at the balance sheet date, and therefore that the outstanding principal and accrued interest of $78,809,300 and $110,435,600 at June 30, 2016 and December 31, 2015, respectively, approximate its fair values on such dates. The fair value of the Company's outstanding balance of its Credit Facility would be categorized as Level 3 under the GAAP fair value hierarchy.

(d) Finance Leases

The Company has five aircraft finance leases that contain lessee purchase options at prices substantially below the assets' estimated residual values at the exercise date for the option. Consequently, the Company considers the purchase options to be bargain purchase options and has classified the leases as sales-type finance leases for financial accounting purposes. The Company reports the discounted present value of (i) future minimum lease payments (including the bargain purchase option) and (ii) any residual value not subject to a bargain purchase option as a finance lease receivable on its balance sheet and accrues interest on the balance of the finance lease receivable based on the interest rate inherent in the applicable lease over the term of the lease. For sales-type finance leases, the Company recognizes the difference between the net book value of the aircraft and the net investment in sales-type finance leases, less any initial direct costs and lease incentives, as a gain or loss.

The Company recognized interest earned on finance leases in the amount of $187,000 and $91,400 in the quarters ended June 30, 2016 and 2015, respectively and $372,100 and $91,400 in the six months ended June 30, 2016 and 2015, respectively.

(e) Recent Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-13, Financial Instruments -- Credit Losses (Topic 326) ("ASU 2016-13"), which will modify accounting for credit losses on most financial assets measured at amortized cost, including net investment in leases. Unlike current accounting, which delays credit loss recognition until a probable loss is incurred, the new model will use a current expected credit loss ("CECL") model that will estimate future credit losses over the entire term of the financial instrument. As such, it is generally expected that adoption of the CECL model will result in earlier recognition of credit losses than current GAAP. The Company will be required to adopt ASU 2016-13 for its yearly and interim periods beginning after December 15, 2019, although adoption in the preceding year and periods is permitted. The Company has not yet estimated the impact of adoption of this standard on its financial statements.