Significant Accounting Policies	6 Months Ended
Jun. 30, 2017
Significant Accounting Policies [Abstract]
Significant Accounting Policies	A. Significant Accounting Policies Basis of Presentation Unless we have indicated otherwise, or the context otherwise requires, references in this report to “GAMCO Investors, Inc.,” “GAMCO,” “the Company,” “GBL,” “we,” “us” and “our” or similar terms are to GAMCO Investors, Inc., its predecessors and its subsidiaries. The unaudited interim condensed consolidated financial statements of GAMCO included herein have been prepared in conformity with generally accepted accounting principles (“GAAP”) in the United States for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by U.S. GAAP in the United States for complete financial statements. In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all adjustments, which are of a normal recurring nature, necessary for a fair presentation of financial position, results of operations and cash flows of GAMCO for the interim periods presented and are not necessarily indicative of a full year’s results. The interim condensed consolidated financial statements include the accounts of GAMCO and its subsidiaries. Intercompany accounts and transactions are eliminated. These interim condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016. Use of Estimates The preparation of the interim condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported on the interim condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Recent Accounting Developments In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, "Revenue from Contracts with Customers," which supersedes the revenue recognition requirements in the Accounting Standards Codification ("Codification") Topic 605, Revenue Recognition, and most industry-specific guidance throughout the industry topics of the Codification. The core principle of the new ASU No. 2014-09 is for companies to recognize revenue from the transfer of goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard provides a five-step approach to be applied to all contracts with customers and also requires expanded disclosures about revenue recognition. In March 2016, the FASB issued revised guidance which clarifies the guidance related to (a) determining the appropriate unit of account under the revenue standard’s principal versus agent guidance and (b) applying the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. In April 2016, the FASB issued an amendment to provide more detailed guidance including additional implementation guidance and examples related to a) identifying performance obligations and b) licenses of intellectual property. In May 2016, the FASB amended the standard to clarify the guidance on assessing collectability, presenting sales taxes, measuring noncash consideration, and certain transition matters. This new guidance will be effective for the Company's first quarter of 2018 and requires either a full retrospective or a modified retrospective approach to adoption. The Company’s implementation analysis is ongoing; however, it does not expect the adoption of the guidance to have a significant effect on the timing of the recognition of revenue. The Company is currently evaluating performance obligations and the related transaction costs. The Company is also reviewing and preparing for the enhanced disclosure requirements of the standard. The overall effect upon adoption may change based on further analysis and implementation efforts. The Company has not yet determined which transition method it will use. In January 2016, the FASB issued ASU 2016-01, which amends the guidance in U.S. GAAP on the classification and measurement of financial instruments. Although the ASU retains many current requirements, it significantly revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. The ASU also amends certain disclosure requirements associated with the fair value of financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. To adopt the amendments, entities will be required to make a cumulative-effect adjustment to beginning retained earnings as of the beginning of the fiscal year in which the guidance is effective. This new guidance will be effective for the Company’s first quarter of 2018. Upon adoption of this guidance, changes in the fair value of the Company’s available-for-sale investments will be reported through earnings rather than through other comprehensive income. In February 2016, the FASB issued ASU 2016-02, which amends the guidance in U.S. GAAP for the accounting for leases. ASU 2016-02 requires a lessee to recognize assets and liabilities arising from most operating leases in the condensed consolidated statement of financial position. It requires these operating leases to be recorded on the balance sheet as right of use assets and offsetting lease liability obligations. This new guidance will be effective for the Company’s first quarter of 2019. The Company is currently evaluating this guidance and the impact it will have on its consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU 2016-09, which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. For public companies, the ASU is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. The Company adopted this guidance on January 1, 2017 without a material impact to the consolidated financial statements. Please see Note D. In August 2016, the FASB issued ASU 2016-15, which adds and clarifies guidance on the classification of certain cash receipts and payments in the consolidated statements of cash flows. This guidance is intended to unify the currently diverse presentations and classifications, which address eight classification issues related to the statement of cash flows, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This new guidance will be effective for the Company’s first quarter of 2018 and requires a retrospective approach to adoption. The Company is currently evaluating the potential effect of this new guidance on its condensed consolidated financial statements and the related disclosures. In January 2017, the FASB issued ASU 2017-04 to simplify the process used to test for goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. This new guidance will be effective for the Company’s first quarter of 2020. The Company is currently evaluating the potential effect of this new guidance on its condensed consolidated financial statements and related disclosures. On May 10, 2017, the FASB issued ASU 2017-09, which amends the scope of modification accounting for share-based payment arrangements. The ASU provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting under ASC 718. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. For all entities, the ASU is effective for annual reporting periods, including interim periods within those annual reporting periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period. This ASU, which we did not early adopt, would not have impacted the accounting for the acceleration of vesting of restricted stock awards during the quarter ended June 30, 2017.

A. Significant Accounting Policies

Basis of Presentation

Unless we have indicated otherwise, or the context otherwise requires, references in this report to “GAMCO Investors, Inc.,” “GAMCO,” “the Company,” “GBL,” “we,” “us” and “our” or similar terms are to GAMCO Investors, Inc., its predecessors and its subsidiaries.

The unaudited interim condensed consolidated financial statements of GAMCO included herein have been prepared in conformity with generally accepted accounting principles (“GAAP”) in the United States for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by U.S. GAAP in the United States for complete financial statements. In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all adjustments, which are of a normal recurring nature, necessary for a fair presentation of financial position, results of operations and cash flows of GAMCO for the interim periods presented and are not necessarily indicative of a full year’s results.

The interim condensed consolidated financial statements include the accounts of GAMCO and its subsidiaries. Intercompany accounts and transactions are eliminated.

These interim condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016.

Use of Estimates

The preparation of the interim condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported on the interim condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

Recent Accounting Developments

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, "Revenue from Contracts with Customers," which supersedes the revenue recognition requirements in the Accounting Standards Codification ("Codification") Topic 605, Revenue Recognition, and most industry-specific guidance throughout the industry topics of the Codification. The core principle of the new ASU No. 2014-09 is for companies to recognize revenue from the transfer of goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard provides a five-step approach to be applied to all contracts with customers and also requires expanded disclosures about revenue recognition. In March 2016, the FASB issued revised guidance which clarifies the guidance related to (a) determining the appropriate unit of account under the revenue standard’s principal versus agent guidance and (b) applying the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. In April 2016, the FASB issued an amendment to provide more detailed guidance including additional implementation guidance and examples related to a) identifying performance obligations and b) licenses of intellectual property. In May 2016, the FASB amended the standard to clarify the guidance on assessing collectability, presenting sales taxes, measuring noncash consideration, and certain transition matters. This new guidance will be effective for the Company's first quarter of 2018 and requires either a full retrospective or a modified retrospective approach to adoption. The Company’s implementation analysis is ongoing; however, it does not expect the adoption of the guidance to have a significant effect on the timing of the recognition of revenue. The Company is currently evaluating performance obligations and the related transaction costs. The Company is also reviewing and preparing for the enhanced disclosure requirements of the standard. The overall effect upon adoption may change based on further analysis and implementation efforts. The Company has not yet determined which transition method it will use.

In January 2016, the FASB issued ASU 2016-01, which amends the guidance in U.S. GAAP on the classification and measurement of financial instruments. Although the ASU retains many current requirements, it significantly revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. The ASU also amends certain disclosure requirements associated with the fair value of financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. To adopt the amendments, entities will be required to make a cumulative-effect adjustment to beginning retained earnings as of the beginning of the fiscal year in which the guidance is effective. This new guidance will be effective for the Company’s first quarter of 2018. Upon adoption of this guidance, changes in the fair value of the Company’s available-for-sale investments will be reported through earnings rather than through other comprehensive income.

In February 2016, the FASB issued ASU 2016-02, which amends the guidance in U.S. GAAP for the accounting for leases. ASU 2016-02 requires a lessee to recognize assets and liabilities arising from most operating leases in the condensed consolidated statement of financial position. It requires these operating leases to be recorded on the balance sheet as right of use assets and offsetting lease liability obligations. This new guidance will be effective for the Company’s first quarter of 2019. The Company is currently evaluating this guidance and the impact it will have on its consolidated financial statements and related disclosures.

In March 2016, the FASB issued ASU 2016-09, which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. For public companies, the ASU is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. The Company adopted this guidance on January 1, 2017 without a material impact to the consolidated financial statements. Please see Note D.

In August 2016, the FASB issued ASU 2016-15, which adds and clarifies guidance on the classification of certain cash receipts and payments in the consolidated statements of cash flows. This guidance is intended to unify the currently diverse presentations and classifications, which address eight classification issues related to the statement of cash flows, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This new guidance will be effective for the Company’s first quarter of 2018 and requires a retrospective approach to adoption. The Company is currently evaluating the potential effect of this new guidance on its condensed consolidated financial statements and the related disclosures.

In January 2017, the FASB issued ASU 2017-04 to simplify the process used to test for goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. This new guidance will be effective for the Company’s first quarter of 2020. The Company is currently evaluating the potential effect of this new guidance on its condensed consolidated financial statements and related disclosures.

On May 10, 2017, the FASB issued ASU 2017-09, which amends the scope of modification accounting for share-based payment arrangements. The ASU provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting under ASC 718. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. For all entities, the ASU is effective for annual reporting periods, including interim periods within those annual reporting periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period. This ASU, which we did not early adopt, would not have impacted the accounting for the acceleration of vesting of restricted stock awards during the quarter ended June 30, 2017.