Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions The following is a summary of certain related party transactions. GGCP Holdings, LLC, a subsidiary of GGCP, which is majority-owned by Mr. Gabelli, owns a majority of the outstanding shares of the Company’s Class B Stock. As of both December 31, 2020 and 2019, such ownership represented approximately 92% of the combined voting power of the outstanding common stock and approximately 67% of the equity interest. As of December 31, 2020 and 2019, AC and its subsidiaries own approximately 2.8 million and 2.9 million shares, respectively, of the Company’s Class A Stock representing approximately 1% and 1%, respectively, of the combined voting power and approximately 10% and 11%, respectively, of the equity interest. AC is majority-owned by GGCP Holdings, LLC. Accordingly, Mr. Gabelli is deemed to control GBL. Leases The Company leases an approximately 60,000 square foot building located at One Corporate Center, Rye, New York as one of its principal offices (the “Building”) from an entity controlled by members of the Chairman’s family. See Leases within Note 10 for further details. The Company sub-leases approximately 3,300 square feet in the Building to LICT Corporation, a company for which Mr. Gabelli serves as Chairman and CEO, which pays rent at the base rate of $28 per square foot plus $3 per square foot for electricity, subject to adjustment for increases in taxes and other operating expenses. The total amounts received in 2020 and 2019 for rent and other expenses under this lease were $120,384 and $115,573, respectively, which were recorded in other operating expenses as a credit on the consolidated statements of income. Concurrent with the extension of the lease on the Building during 2008, the Company and LICT Corporation further agreed to extend the term of the sub-lease until December 2023 on the same terms and conditions. The Company also sub-leases approximately 1,600 square feet in the Building to Teton, a company which is majority owned by GGCP Holdings LLC. Teton pays rent at the base rate of $37.75 per square foot plus $3 per square foot for electricity, subject to adjustment for increases in taxes and other operating expenses. The total amount received in 2020 and 2019 for rent and other expenses under this lease were $69,951 and $67,752, respectively, which were recorded in other operating expenses as a credit on the consolidated statements of income. For January 1, 2019 through August 4, 2020, the Company sub-leased approximately 13,800 square feet in the Building to AC. For August 5, 2020 through December 31, 2020, the Company sub-leased approximately 5,200 square feet in the Building to AC. AC pays rent at the base rate of $22.32 per square foot plus $3 per square foot for electricity. The total amount received in 2020 and 2019 for rent and other expenses under this lease was $143,588 and $485,333, respectively, which was recorded in distribution fees and other income on the consolidated statements of income. For August 5, 2020 through December 31, 2020, the Company sub-leased approximately 2,800 square feet in the Building to Morgan Group Holding Co., a subsidiary of GGCP. The total amount received in 2020 for rent and other expenses under this lease was $40,531, which was recorded in distribution fees and other income on the consolidated statements of income. Effective September 1, 2019, the Company leases office space located at 191 Mason Street, Greenwich, Connecticut from AC for its other principal office. During 2020 and 2019, the Company paid AC $116,400 and $29,100, respectively, in rent per year. Investment Advisory Services GAMCO has entered into agreements to provide advisory and administrative services to MJG Associates, Inc., which is wholly-owned by Mr. Gabelli, with respect to the private investment funds managed by them. Pursuant to such agreements, MJG Associates, Inc. paid GAMCO $10,000 (excluding reimbursement of expenses) for each of the years 2020 and 2019. The Company serves as the investment advisor for the Funds and earns advisory fees based on predetermined percentages of the average net assets of the Funds. In addition, G.distributors has entered into distribution agreements with each of the Funds. It also distributes funds managed by Teton and its affiliates. As principal distributor, G.distributors incurs certain promotional and distribution costs related to the sale of Fund shares, for which it receives a distribution fee from the Funds or reimbursement from the investment advisor. For 2020 and 2019, the Company received $23.1 million and $29.2 million, respectively, in distributions fees. Advisory and distribution fees receivable from the Funds were approximately $24.4 million and $31.0 million at December 31, 2020 and 2019, respectively. Pursuant to an agreement between Gabelli & Company Investment Advisers, Inc. (“GCI”) (formerly called Gabelli Securities, Inc.) and Gabelli Funds, Gabelli Funds pays to GCI 90% of the net revenues received by Gabelli Funds related to being the advisor to the SICAV. Net revenues are defined as gross advisory fees less expenses related to payouts and expenses of the SICAV paid by Gabelli Funds. The amounts paid by Gabelli Funds to GCI for 2020 and 2019 were $7.2 million and $7.6 million, respectively, and were included in other operating expenses on the consolidated statements of income. Compensation Immediately preceding the initial public offering in February 1999, GBL and the Company’s Chairman and CEO, Mr. Gabelli, entered into an employment agreement. On February 6, 2008, Mr. Gabelli entered into an amended and restated employment agreement (as amended, the “2008 Employment Agreement”) with the Company, which was initially approved by the Company’s shareholders on November 30, 2007 and approved again on May 6, 2011, May 5, 2015, and June 5, 2020. Under the terms of this agreement and consistent with the Firm’s practice since its inception in 1977, Mr. Gabelli is entitled to receive a percentage of revenues or net operating contribution, which are substantially derived from AUM, as compensation relating to or generated by the following activities: (i) managing or overseeing the management of various investment companies, (ii) attracting mutual fund shareholders, (iii) attracting and managing Institutional and PWM clients, and (iv) otherwise generating revenues for the Company. Such payments are made in a manner and at rates as agreed to from time to time by GAMCO, which rates have been and generally will be the same as those received by other professionals at GAMCO performing similar services. With respect to the Institutional and PWM and Funds advisory businesses, the Company pays out up to 40% of the revenues or net operating contribution to the portfolio managers and marketing teammates who introduce, service, or generate such business, with payments involving the Institutional and PWM accounts being typically based on revenues and payments involving the Funds being typically based on net operating contribution. Mr. Gabelli has agreed that while he is employed by the Company, he will not provide investment management services outside of GAMCO, except for certain permitted accounts as defined under the agreement. The 2008 Employment Agreement may not be amended without the approval of the Compensation Committee and Mr. Gabelli. Mr. Gabelli receives compensation in the form of a management fee for managing the Company. The management fee is incentive-based and entirely variable compensation in the amount of 10% of the aggregate pre-tax profits, which is paid to Mr. Gabelli or his designee for acting as CEO pursuant to his 2008 Employment Agreement so long as he is an executive of GBL and devotes the substantial majority of his working time to the business. During 2020, Mr. Gabelli elected to waive $14.7 million in compensation that he would otherwise have been entitled to under his 2008 Employment Agreement relating to the period of July 1, 2020 to November 10, 2020. During 2019, Mr. Gabelli elected to waive $27.2 million in compensation that he would otherwise have been entitled to under his 2008 Employment Agreement relating to the periods of January 1, 2019 to March 31, 2019 and September 1, 2019 to November 30, 2019. Other For 2020 and 2019, the Company incurred variable costs (but not the fixed costs) of $134,000 and $317,000, respectively, for actual usage relating to the use of aircraft in which GGCP owns the fractional interests. GBL and Teton entered into a transitional administrative and management service agreement in connection with the spin-off of Teton from GBL that formalized certain arrangements. Effective January 1, 2011, Teton and GBL renegotiated the terms of the sub-administration agreement from a flat 0.20% on the average net assets of the mutual funds managed by Teton to 0.20% on the first $370 million in average net assets, 0.12% on the next $630 million in average net assets, and 0.10% on average net assets in excess of $1 billion, as compensation for providing mutual fund administration services. Additionally, Teton paid to GBL an administrative services fee of $4,167 per month. During 2020 and 2019, there was $1.5 million and $2.0 million, respectively, included in distribution fees and other income on the consolidated statements of income. Effective January 1, 2014, GAMCO Asset and Gabelli Funds each entered into a research services agreement with G.research, LLC, a wholly-owned subsidiary of GCI, for G.research, LLC to provide them with the same types of research services that it provides to its other clients. This agreement ended December 31, 2019. For the year ended December 31, 2019, GAMCO Asset and Gabelli Funds both paid G.research, LLC $750 thousand. GBL and AC entered into a transitional administrative and management services agreement in connection with the spin-off of AC from GBL on November 30, 2015. The agreement calls for GBL to provide to AC certain administrative services including but not limited to: human resources, compliance, legal, payroll, information technology, and operations. All services provided under the agreement by GBL to AC or by AC to GBL are charged at cost. The agreement is terminable by either party on 30 days’ prior written notice to the other party and has a term of twelve months.