Basis of Presentation	6 Months Ended
Jun. 30, 2018
Nature Of Business And Significant Accounting Policies [Abstract]
Basis Of Presentation	Note 1. Basis of Presentation The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions and regulations of the Securities and Exchange Commission to Form 10-Q. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. This report should be read together with the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, including the audited financial statements and footnotes therein. Management believes that the unaudited financial statements include all adjustments, consisting of normal recurring accruals, necessary to fairly state the financial position and results of operations as of June 30, 2018 and for the three and six-month periods then ended in accordance with accounting principles generally accepted in the United States of America. The results of interim periods may not be indicative of results to be expected for the year. Nature of Business Electro-Sensors, Inc. manufactures and markets a complete line of monitoring and control systems for a variety of industrial machinery. The Company uses leading-edge technology to continuously improve its products and make them easier to use, with the goal of manufacturing the industry-preferred product for every market served. The Company sells these products through an internal sales staff, manufacturers’ representatives, and distributors to a wide variety of industries that use the products in a variety of applications to monitor process machinery operations. The Company markets its products to customers located throughout the United States, Canada, Latin America, Europe, and Asia. Revenue Recognition On January 1, 2018, the Company adopted Accounting Standards Codification (ASC) Revenue from Contracts with Customers and all related amendments (the Standard), for all contracts using the modified retrospective method. The Standard implements a five-step process for revenue recognition that focuses on transfer of control and defines a contract as “an agreement between two or more parties that creates legally enforceable rights and obligations." The adoption of the Standard did not materially impact the timing and measurement of revenue recognition. As a result, we did not recognize a cumulative effect adjustment to the opening balance of retained earnings. At contract inception, the Company assesses the goods and services promised to a customer and identifies a performance obligation for each promised good or service that is distinct. In addition, the transaction price for each performance obligation is determined at contract inception. Our contracts, generally in the form of a purchase order, specify the product or service that is promised to the customer. The typical contract life is less than one month and contains a single performance obligation, to provide conforming goods or services to the customer. Product revenue is recognized at the point in time when control of the product is transferred to the customer, which typically occurs when products are shipped. Service revenue is recognized at the point in time when the service has been provided. Fair Value Measurements The carrying value of trade receivables, accounts payable, and other financial working capital items approximates fair value at June 30, 2018 and December 31, 2017, due to the short maturity nature of these instruments. Stock-Based Compensation The Company records compensation expense for stock options based on the estimated fair value of the options on the date of grant using the Black-Scholes-Merton (“BSM”) option pricing model. The Company uses historical data, among other factors, to estimate the expected price volatility, the expected option life, and the expected forfeiture rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for the estimated life of the option. As of June 30, 2018, there was approximately $11 of unrecognized compensation expense related to unvested stock options. The Company expects to recognize this expense over the next two years. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Significant estimates, including the underlying assumptions, consist of economic lives of long-lived assets, realizability of trade receivables, valuation of deferred tax assets/liabilities, inventory, investments, contingent earn-out, and stock compensation expense. It is at least reasonably possible that these estimates may change in the near term. Recently Adopted Accounting Pronouncement In January 2016, the FASB issued Accounting Standards Update No. 2016-01 (ASU 2016-01) "Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities," which amends various aspects of the recognition, measurement, presentation, and disclosure of financial instruments. The Company adopted ASU 2016-01 as of January 1, 2018 using the modified retrospective method for marketable equity securities. This resulted in a $7 reclassification of net unrealized losses from accumulated other comprehensive gain (AOCI) to retained earnings. The adoption of ASU 2016-01 increases the volatility of non-operating income, as a result of the remeasurement of the equity securities. For further information on unrealized gains from equity securities, see Note 2. Net Loss per Common Share Basic and diluted net loss per common share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period. For all periods presented, the common shares underlying stock options have been excluded from the calculation because their effect would be anti-dilutive. Therefore, the weighted-average shares outstanding used to calculate both basic and diluted loss per common shares are the same. For the three and six months ended June 30, 2018, 7,318 and 7,474 option share equivalents, respectively, have been excluded from the computations of diluted weighted-average shares outstanding. Reclassification Certain items related to freight costs in the 2017 financial statements have been reclassified to conform to the 2018 presentation. These reclassifications had no effect on stockholders' equity, net income, or cash flows.

Note 1. Basis of Presentation

The accompanying unaudited financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions and regulations of the Securities and Exchange Commission to Form 10-Q. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements.

This report should be read together with the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, including the audited financial statements and footnotes therein.

Management believes that the unaudited financial statements include all adjustments, consisting of normal recurring accruals, necessary to fairly state the financial position and results of operations as of June 30, 2018 and for the three and six-month periods then ended in accordance with accounting principles generally accepted in the United States of America. The results of interim periods may not be indicative of results to be expected for the year.

Nature of Business

Electro-Sensors, Inc. manufactures and markets a complete line of monitoring and control systems for a variety of industrial machinery. The Company uses leading-edge technology to continuously improve its products and make them easier to use, with the goal of manufacturing the industry-preferred product for every market served. The Company sells these products through an internal sales staff, manufacturers’ representatives, and distributors to a wide variety of industries that use the products in a variety of applications to monitor process machinery operations. The Company markets its products to customers located throughout the United States, Canada, Latin America, Europe, and Asia.

Revenue Recognition

On January 1, 2018, the Company adopted Accounting Standards Codification (ASC) Revenue from Contracts with Customers and all related amendments (the Standard), for all contracts using the modified retrospective method. The Standard implements a five-step process for revenue recognition that focuses on transfer of control and defines a contract as “an agreement between two or more parties that creates legally enforceable rights and obligations." The adoption of the Standard did not materially impact the timing and measurement of revenue recognition. As a result, we did not recognize a cumulative effect adjustment to the opening balance of retained earnings.

At contract inception, the Company assesses the goods and services promised to a customer and identifies a performance obligation for each promised good or service that is distinct. In addition, the transaction price for each performance obligation is determined at contract inception. Our contracts, generally in the form of a purchase order, specify the product or service that is promised to the customer. The typical contract life is less than one month and contains a single performance obligation, to provide conforming goods or services to the customer. Product revenue is recognized at the point in time when control of the product is transferred to the customer, which typically occurs when products are shipped. Service revenue is recognized at the point in time when the service has been provided.

Fair Value Measurements

The carrying value of trade receivables, accounts payable, and other financial working capital items approximates fair value at June 30, 2018 and December 31, 2017, due to the short maturity nature of these instruments.

Stock-Based Compensation

The Company records compensation expense for stock options based on the estimated fair value of the options on the date of grant using the Black-Scholes-Merton (“BSM”) option pricing model. The Company uses historical data, among other factors, to estimate the expected price volatility, the expected option life, and the expected forfeiture rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for the estimated life of the option.

As of June 30, 2018, there was approximately $11 of unrecognized compensation expense related to unvested stock options. The Company expects to recognize this expense over the next two years.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Significant estimates, including the underlying assumptions, consist of economic lives of long-lived assets, realizability of trade receivables, valuation of deferred tax assets/liabilities, inventory, investments, contingent earn-out, and stock compensation expense. It is at least reasonably possible that these estimates may change in the near term.

Recently Adopted Accounting Pronouncement

In January 2016, the FASB issued Accounting Standards Update No. 2016-01 (ASU 2016-01) "Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities," which amends various aspects of the recognition, measurement, presentation, and disclosure of financial instruments. The Company adopted ASU 2016-01 as of January 1, 2018 using the modified retrospective method for marketable equity securities. This resulted in a $7 reclassification of net unrealized losses from accumulated other comprehensive gain (AOCI) to retained earnings. The adoption of ASU 2016-01 increases the volatility of non-operating income, as a result of the remeasurement of the equity securities. For further information on unrealized gains from equity securities, see Note 2.

Net Loss per Common Share

Basic and diluted net loss per common share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period. For all periods presented, the common shares underlying stock options have been excluded from the calculation because their effect would be anti-dilutive. Therefore, the weighted-average shares outstanding used to calculate both basic and diluted loss per common shares are the same.

For the three and six months ended June 30, 2018, 7,318 and 7,474 option share equivalents, respectively, have been excluded from the computations of diluted weighted-average shares outstanding.

Reclassification

Certain items related to freight costs in the 2017 financial statements have been reclassified to conform to the 2018 presentation. These reclassifications had no effect on stockholders' equity, net income, or cash flows.