Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Safeguard and all of its subsidiaries in which a controlling financial interest is maintained. All intercompany accounts and transactions are eliminated in consolidation.
Principles of Accounting for Ownership Interests in Companies	Impairment of Ownership Interests and Advances On a periodic basis, but no less frequently than quarterly, the Company evaluates the carrying value of its ownership interests and advances for possible impairment based on achievement of business plan objectives and milestones, the estimated fair value of each company relative to its carrying value, the financial condition and prospects of the company and other relevant factors. The business plan objectives and milestones the Company considers include, among others, those related to financial performance, such as achievement of planned financial results or completion of capital raising activities, and those that are not primarily financial in nature, such as hiring of key employees or the establishment of strategic relationships. Management then determines whether there has been an other than temporary decline in the value of its ownership interest in the company. Impairment is measured as the amount by which the carrying value of an asset exceeds its estimated fair value. The estimated fair value of privately held companies is generally determined based on the value at which independent third parties have invested or have committed to invest in these companies or based on other valuation methods, including discounted cash flows, valuation of comparable public companies and the valuation of acquisitions of similar companies. Impairment charges related to equity method companies are included in Equity income (loss) in the Consolidated Statements of Operations. Impairment charges related to non-equity method companies and funds are included in Other income (loss), net in the Consolidated Statements of Operations. The reduced cost basis of a previously impaired company accounted for using the Equity method are not written-up if circumstances suggest the value of the company has subsequently recovered. Principles of Accounting for Ownership Interests in Companies The Company accounts for its ownership interests using one of the following methods: Equity or Other. The accounting method applied is generally determined by the degree of the Company's influence over the entity, primarily determined by our voting interest in the entity. In addition to holding voting and non-voting equity and debt securities, the Company also periodically makes advances to its companies in the form of promissory notes which are included in the Ownership interests and advances on the Consolidated Balance Sheets. Equity Method. The Company accounts for ownership interests whose results are not consolidated, but over which it exercises significant influence, under the equity method of accounting. Whether or not the Company exercises significant influence with respect to an ownership interest depends on an evaluation of several factors including, among others, representation on the board of directors and our ownership level, which is generally a 20% to 50% interest in the voting securities of a company, including voting rights associated with the Company’s holdings in common, preferred and other convertible instruments in the company. Under the equity method of accounting, the Company does not reflect a company’s financial statements within our Consolidated Financial Statements; however, our share of the income or loss of such company is reflected in Equity income (loss) in the Consolidated Statements of Operations. The Company includes the carrying value of equity method companies in Ownership interests and advances on the Consolidated Balance Sheets. Any excess of the Company’s cost over its underlying interest in the net assets of equity method companies that is allocated to intangible assets is amortized over the estimated useful lives of the related intangible assets. The Company reflects its share of the income or loss of the equity method companies on a one quarter lag. This reporting lag could result in a delay in recognition of the impact of changes in the business or operations of these companies. When the Company’s carrying value in an equity method company is reduced to zero, the Company records no further losses in its Consolidated Statements of Operations unless the Company has an outstanding guarantee obligation or has committed additional funding to such equity method company. When such equity method company subsequently reports income, the Company will not record its share of such income until it exceeds the amount of the Company’s share of losses not previously recognized. Other Method. We account for our equity interests in companies which are not accounted for under the equity method as equity securities without readily determinable fair values. We estimate the fair value of these securities based on our original cost less impairments, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Under this method, our share of the income or losses of such companies is not included in our Consolidated Statements of Operations. We include the carrying value of these investments in Ownership interests and advances on the Consolidated Balance Sheets.
Accounting Estimates	Accounting Estimates The preparation of the Consolidated Financial Statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and judgments that affect amounts reported in the financial statements and accompanying notes. Actual results may differ from these estimates. These estimates include the evaluation of the recoverability of the Company’s ownership interests and advances, the fair value of the credit facility repayment feature derivative, the current portion of the credit facility debt, the recoverability of deferred tax assets, stock-based compensation and commitments and contingencies. Management evaluates its estimates on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable under the circumstances. Certain amounts recorded to reflect the Company’s share of income or losses for companies accounted for under the equity method are based on unaudited results of operations of those companies and may require adjustments in the future when audits of these entities’ financial statements are completed. It is reasonably possible that the Company’s accounting estimates with respect to the ultimate recoverability of the carrying value of the Company’s ownership interests and advances could change in the near term and that the effect of such changes on the financial statements could be material. At December 31, 2019, the Company believes the carrying value of the Company’s ownership interests and advances is not impaired, although there can be no assurance that the Company’s future results will confirm this assessment, that a significant write-down or write-off will not be required in the future or that a significant loss will not be recorded in the future upon the sale of a company.
Cash and Cash Equivalents and Marketable Securities	Cash and Cash Equivalents and Marketable Securities The Company considers all highly liquid instruments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits that are readily convertible into cash. The Company determines the appropriate classification of marketable securities at the time of purchase and reevaluates such designation as of each balance sheet date. Held-to-maturity securities were carried at amortized cost, which approximated fair value. Marketable securities consisted of held-to-maturity securities, primarily consisting of government agency bonds, commercial paper and certificates of deposits. Marketable securities with a maturity date greater than one year from the balance sheet date would be considered long-term. The Company has not experienced any significant losses on cash equivalents and does not believe it is exposed to any significant credit risk on cash and cash equivalents.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash Restricted cash equivalents represents cash required to be set aside by a contractual agreement as a shareholder representative.
Financial Instruments	Financial Instruments The Company’s financial instruments (principally cash and cash equivalents, marketable securities, accounts receivable, notes receivable, accounts payable and accrued expenses) are carried at cost, which approximates fair value due to the short-term maturity of these instruments. The Company’s long-term debt was carried at cost.
Property and Equipment	Property and Equipment Property and equipment represents right-of-use assets resulting from the adoption of Accounting Standards Update ("ASU") No. 2016-02, Leases, and other previously existing leasehold improvements. The leasehold improvements were amortized over the shorter of the estimated useful lives or the expected remaining term of the lease. The right-of-use assets are reduced over the remaining term of the applicable lease (principally April 2026) in a manner that results in a straight-line lease expense, when combined with the interest factor on the lease liability.
Lease liability	Lease liability The initial lease liability represents the present value of the fixed escalating lease payments through April 2026 associated with the Company's prior corporate headquarters operating office lease.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method whereby deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The Company measures deferred tax assets and liabilities using enacted tax rates in effect for the year in which the temporary differences are expected to be recovered or settled. The Company recognizes the effect on deferred tax assets and liabilities of a change in tax rates in income in the period of the enactment date. The Company provides a valuation allowance against the net deferred tax asset for amounts which are not considered more likely than not to be realized.
Net Income (Loss) Per Share	Net Income (Loss) Per Share The Company computes net income (loss) per share using the weighted average number of common shares outstanding during each year. The Company includes in diluted net income (loss) per share common stock equivalents (unless anti-dilutive) which would arise from the exercise of stock options and conversion of other convertible securities and adjusted, if applicable, for the effect on net income (loss) of such transactions. Diluted net income (loss) per share calculations adjust net income (loss) for the dilutive effect of common stock equivalents and convertible securities issued by the Company’s consolidated or equity method companies.
Segment Information	Segment Information The Company operates as one operating segment based upon the similar nature of its technology-driven companies, the functional alignment of the organizational structure, and the reports that are regularly reviewed by the chief operating decision maker for the purpose of assessing performance and allocating resources.
Reclassifications	Reclassifications Certain prior period amounts within Prepaid expenses and other current assets aggregating $2.1 million have been reclassified to Other assets to conform with current year presentation.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 and related subsequent amendments outline a single comprehensive model to use to account for revenue arising from contracts with customers and supersede most current revenue recognition guidance. For public companies, the guidance was effective for annual periods beginning after December 15, 2017 and any interim periods that fall within that reporting period. For nonpublic companies, the guidance is effective for annual periods beginning after December 15, 2018 and interim periods within annual periods beginning after December 15, 2019 with early adoption permitted. As the new standard will supersede most existing revenue guidance, it could impact revenue and cost recognition for companies in which we hold an ownership interest. Any change in revenue or cost recognition for companies in which we hold an ownership interest could affect the Company's recognition of its share of the results of its equity method companies. On July 20, 2017, the SEC staff observer at the FASB’s Emerging Issues Task Force ("EITF") meeting announced that the SEC staff will not object if a private company equity method investee meeting the definition of a public business entity that otherwise would not meet the definition of a public business entity except for the inclusion of its financial statements or financial information in another entity’s filings with the SEC, uses private company adoption dates for the new revenue standard. As a result, the Company's private, calendar year companies will adopt the new revenue standard for the year ending December 31, 2019. The impact of adoption of the new revenue standard will be reflected in the Company’s financial results for the interim and annual reporting periods beginning in 2020 on a one quarter-lag basis. In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842). The guidance in ASU No. 2016-02 requires that a lessee recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. As with previous guidance, there continues to be a differentiation between finance leases and operating leases, however this distinction now primarily relates to differences in the manner of expense recognition over time and in the classification of lease payments in the statement of cash flows. Lease assets and liabilities arising from both finance and operating leases will be recognized in the statement of financial position. The transitional guidance for adopting the requirements of ASU No. 2016-02 calls for a modified retrospective approach that includes a number of optional practical expedients that entities may elect to apply. The guidance in ASU No. 2016-02 became effective for the Company on January 1, 2019. The Company elected the package of practical expedients permitted under the transition guidance within the new standard, which, among other things, allowed the Company to carry forward its historical lease classification. In addition, the Company has elected to exempt short term leases that qualify from recognizing right of use assets or lease liabilities, and has elected to not separate lease and non-lease components for all leases where it is the lessee. The Company’s non-lease components are primarily related to utility and maintenance costs, which are typically variable in nature and are expensed in the period incurred. As of January 1, 2019, the Company's only material long-term lease was for its former corporate headquarters in Radnor, PA under a lease expiring in 2026. The Company also has immaterial office equipment leases expiring at various dates through 2020. The Company recorded an initial lease liability of $2.9 million, a right-of-use asset of $2.2 million included in property and equipment and eliminated the deferred rent liability of $0.7 million that was previously included in other long-term liabilities.