Equity	12 Months Ended
Dec. 31, 2019
Equity [Abstract]
Equity	8. Equity Shares outstanding were 27.4 million and 29.0 million on December 31, 2019 and 2018, respectively. Voting Rights The holders of class A common stock of GBL (“Class A Stock”) and class B common stock of GBL (“Class B Stock”) have identical rights except that (i) holders of Class A Stock are entitled to one vote per share, while holders of Class B Stock are entitled to ten votes per share, on all matters to be voted on by shareholders in general, and (ii) holders of Class A Stock are not eligible to vote on matters relating exclusively to Class B Stock and vice versa. Stock Award and Incentive Plan The Company maintains a stock award and incentive plan approved by the shareholders (the “Plan”), which is designed to provide incentives which will attract and retain individuals key to the success of GBL through direct or indirect ownership of GBL common stock. A maximum of 7.5 million shares of Class A Stock have been reserved for issuance under the Plan by the Compensation Committee of the Company’s Board of Directors. Benefits under the Plan may be granted in any one or a combination of stock options, stock appreciation rights, restricted stock, restricted stock units, stock awards, dividend equivalents, and other stock or cash based awards. Under the Plan, the Compensation Committee may grant RSAs, each of which entitles the grantee to one share of Class A Stock subject to restrictions, and either incentive or nonqualified stock options, with a term not to exceed ten years from the grant date and at an exercise price that the Compensation Committee may determine, which were recommended by the Company’s Chairman who did not receive any awards. On January 5, 2018, the Compensation Committee accelerated the vesting relating to the remaining 19,400 RSAs outstanding at that time. As a result, GBL recorded an incremental $0.2 million of stock-based compensation expense during 2018. On April 4, 2018, 270,500 RSAs were issued at a grant price of $24.77 per RSA. On May 9, 2018, 10,000 stock options were issued with an exercise price of $25.55. On August 7, 2018, 162,450 RSAs were issued at a grant price of $25.16 per RSA. On September 17, 2018, 5,000 RSAs were issued at a grant price of $25.74 per RSA. On June 30, 2019, 264,900 RSAs were issued at a grant price of $19.17 per RSA. As of December 31, 2019 and 2018, there were 660,950 and 427,650, respectively, of these RSAs outstanding with weighted average grant prices per RSA of $22.67 and $24.93, respectively, and 10,000 of these stock options outstanding with an exercise price of $25.55. For the years ended December 31, 2019 and 2018, the Company recorded approximately $2.8 million and $1.6 million, respectively, in stock based compensation expense, which resulted in the recognition of tax benefits of approximately $0.7 million and $0.4 million, respectively. The total compensation costs related to non-vested awards not yet recognized is approximately $9.7 million as of December 31, 2019. During 2016, in accordance with the deferred compensation agreement (“DCCA”) with Mr. Gabelli for the full year of 2016 (“2016 DCCA”), the Company issued 2,314,695 Restricted Stock Units (“RSUs”), based upon the volume weighted average price (“VWAP”) of the Company’s Class A Stock for 2016 of $32.8187, in satisfaction of Mr. Gabelli’s variable compensation of $76.0 million for 2016. These RSUs vested 100% on January 2, 2020, and a cash payment in the amount of $43.7 million was made to the CEO. This payment was reduced by $32.3 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($18.8812) versus the VWAP over 2016 ($32.8187). For 2019 and 2018, the Company expensed 25%, or $19.0 million, of the 2016 DCCA cost in each year. Notwithstanding its ability to settle the award in stock, given the Company’s intent to pay, and eventual settlement in, cash, in accordance with U.S. GAAP (ASC 718, Compensation—Stock Compensation), the award was accounted for as a liability-classified award and not as an equity-classified award. The liability was remeasured at fair value on each reporting period until the vesting date. Therefore, in accordance with U.S. GAAP, the Company marked to market the RSU payable on December 31, 2019 and 2018 to the closing prices of the Company’s Class A Stock of $19.49 and $16.89, respectively. These mark to market adjustments resulted in a reduction of the RSU expense of $3.2 million and $24.0 million for 2019 and 2018, respectively. On December 23, 2016, GAMCO entered into a DCCA with Mr. Gabelli whereby his variable compensation for the first half of 2017 (“First Half 2017 DCCA”) was in the form of RSUs determined by the VWAP of the Company’s Class A Stock during the first half of 2017. During 2017, in accordance with the First Half 2017 DCCA, the Company issued 1,244,018 RSUs, based upon the VWAP of the Company’s Class A Stock for the first half of 2017 of $29.6596, in satisfaction of Mr. Gabelli’s variable compensation of $36.9 million for that period. These RSUs vested 100% on July 2, 2018, and a cash payment in the amount of $28.3 million was made to the CEO. This payment was after a waiver of $6.0 million by the CEO and a reduction of $2.6 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($27.1837) versus the VWAP over the first half of 2017 ($29.6596). On September 30, 2017, GAMCO entered into a DCCA with Mr. Gabelli whereby his variable compensation for the fourth quarter of 2017 (“Fourth Quarter 2017 DCCA”) was in the form of RSUs determined by the VWAP of the Company’s Class A Stock during the fourth quarter of 2017. During 2017, in accordance with the Fourth Quarter 2017 DCCA, the Company issued 530,662 RSUs, based upon the VWAP of the Company’s Class A Stock for the fourth quarter of 2017 of $29.1875, in satisfaction of Mr. Gabelli’s variable compensation of $15.5 million for that period. These RSUs vested 100% on April 1, 2019, and a cash payment in the amount of $11.0 million was made to the CEO. This payment was reduced by $4.5 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($20.7916) versus the VWAP over the fourth quarter of 2017 ($29.1875). Stock Repurchase Program In March 1999, the Board of Directors established a stock repurchase program (the “Stock Repurchase Program”) to grant management the authority to repurchase shares of Class A Stock. In May and November 2019, the Board of Directors increased the buyback authorization by 1,212,759 and 1,000,000 shares of Class A Stock, respectively. On April 16, 2019 and September 16, 2019, GAMCO repurchased 1.2 million and 70 thousand shares, respectively, of Class A Stock at $21.00 and $20.07 per share, respectively, in private transactions. For the years ended December 31, 2019 and 2018, outside of the private transactions, the Company repurchased 551,675 and 419,995 shares, respectively, at an average price per share of $18.99 and $25.25, respectively. At December 31, 2019, the total shares available under the Stock Repurchase Program to be repurchased in the future were 1,243,135. The Stock Repurchase Program is not subject to an expiration date. Dividends During 2019 and 2018, the Company declared dividends of $0.08 per share to class A and class B shareholders totaling $2.2 million and $2.3 million, respectively. Shelf Registration In April 2018, the SEC declared effective the Company’s “shelf” registration statement on Form S-3 giving the Company the flexibility to sell any combination of senior and subordinate debt securities, convertible debt securities, and equity securities (including common and preferred securities) up to a total amount of $500 million. The shelf is available through April 2021, at which time it may be renewed.

8. Equity

Shares outstanding were 27.4 million and 29.0 million on December 31, 2019 and 2018, respectively.

Voting Rights

The holders of class A common stock of GBL (“Class A Stock”) and class B common stock of GBL (“Class B Stock”) have identical rights except that (i) holders of Class A Stock are entitled to one vote per share, while holders of Class B Stock are entitled to ten votes per share, on all matters to be voted on by shareholders in general, and (ii) holders of Class A Stock are not eligible to vote on matters relating exclusively to Class B Stock and vice versa.

Stock Award and Incentive Plan

The Company maintains a stock award and incentive plan approved by the shareholders (the “Plan”), which is designed to provide incentives which will attract and retain individuals key to the success of GBL through direct or indirect ownership of GBL common stock. A maximum of 7.5 million shares of Class A Stock have been reserved for issuance under the Plan by the Compensation Committee of the Company’s Board of Directors. Benefits under the Plan may be granted in any one or a combination of stock options, stock appreciation rights, restricted stock, restricted stock units, stock awards, dividend equivalents, and other stock or cash based awards. Under the Plan, the Compensation Committee may grant RSAs, each of which entitles the grantee to one share of Class A Stock subject to restrictions, and either incentive or nonqualified stock options, with a term not to exceed ten years from the grant date and at an exercise price that the Compensation Committee may determine, which were recommended by the Company’s Chairman who did not receive any awards.

On January 5, 2018, the Compensation Committee accelerated the vesting relating to the remaining 19,400 RSAs outstanding at that time. As a result, GBL recorded an incremental $0.2 million of stock-based compensation expense during 2018.

On April 4, 2018, 270,500 RSAs were issued at a grant price of $24.77 per RSA. On May 9, 2018, 10,000 stock options were issued with an exercise price of $25.55. On August 7, 2018, 162,450 RSAs were issued at a grant price of $25.16 per RSA. On September 17, 2018, 5,000 RSAs were issued at a grant price of $25.74 per RSA. On June 30, 2019, 264,900 RSAs were issued at a grant price of $19.17 per RSA.

As of December 31, 2019 and 2018, there were 660,950 and 427,650, respectively, of these RSAs outstanding with weighted average grant prices per RSA of $22.67 and $24.93, respectively, and 10,000 of these stock options outstanding with an exercise price of $25.55.

For the years ended December 31, 2019 and 2018, the Company recorded approximately $2.8 million and $1.6 million, respectively, in stock based compensation expense, which resulted in the recognition of tax benefits of approximately $0.7 million and $0.4 million, respectively.

The total compensation costs related to non-vested awards not yet recognized is approximately $9.7 million as of December 31, 2019.

During 2016, in accordance with the deferred compensation agreement (“DCCA”) with Mr. Gabelli for the full year of 2016 (“2016 DCCA”), the Company issued 2,314,695 Restricted Stock Units (“RSUs”), based upon the volume weighted average price (“VWAP”) of the Company’s Class A Stock for 2016 of $32.8187, in satisfaction of Mr. Gabelli’s variable compensation of $76.0 million for 2016. These RSUs vested 100% on January 2, 2020, and a cash payment in the amount of $43.7 million was made to the CEO. This payment was reduced by $32.3 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($18.8812) versus the VWAP over 2016 ($32.8187). For 2019 and 2018, the Company expensed 25%, or $19.0 million, of the 2016 DCCA cost in each year. Notwithstanding its ability to settle the award in stock, given the Company’s intent to pay, and eventual settlement in, cash, in accordance with U.S. GAAP (ASC 718, Compensation—Stock Compensation), the award was accounted for as a liability-classified award and not as an equity-classified award. The liability was remeasured at fair value on each reporting period until the vesting date. Therefore, in accordance with U.S. GAAP, the Company marked to market the RSU payable on December 31, 2019 and 2018 to the closing prices of the Company’s Class A Stock of $19.49 and $16.89, respectively. These mark to market adjustments resulted in a reduction of the RSU expense of $3.2 million and $24.0 million for 2019 and 2018, respectively.

On December 23, 2016, GAMCO entered into a DCCA with Mr. Gabelli whereby his variable compensation for the first half of 2017 (“First Half 2017 DCCA”) was in the form of RSUs determined by the VWAP of the Company’s Class A Stock during the first half of 2017. During 2017, in accordance with the First Half 2017 DCCA, the Company issued 1,244,018 RSUs, based upon the VWAP of the Company’s Class A Stock for the first half of 2017 of $29.6596, in satisfaction of Mr. Gabelli’s variable compensation of $36.9 million for that period. These RSUs vested 100% on July 2, 2018, and a cash payment in the amount of $28.3 million was made to the CEO. This payment was after a waiver of $6.0 million by the CEO and a reduction of $2.6 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($27.1837) versus the VWAP over the first half of 2017 ($29.6596).

On September 30, 2017, GAMCO entered into a DCCA with Mr. Gabelli whereby his variable compensation for the fourth quarter of 2017 (“Fourth Quarter 2017 DCCA”) was in the form of RSUs determined by the VWAP of the Company’s Class A Stock during the fourth quarter of 2017. During 2017, in accordance with the Fourth Quarter 2017 DCCA, the Company issued 530,662 RSUs, based upon the VWAP of the Company’s Class A Stock for the fourth quarter of 2017 of $29.1875, in satisfaction of Mr. Gabelli’s variable compensation of $15.5 million for that period. These RSUs vested 100% on April 1, 2019, and a cash payment in the amount of $11.0 million was made to the CEO. This payment was reduced by $4.5 million resulting from the DCCA being indexed to the GBL stock price and utilizing the lesser of the VWAP on the vesting date ($20.7916) versus the VWAP over the fourth quarter of 2017 ($29.1875).

Stock Repurchase Program

In March 1999, the Board of Directors established a stock repurchase program (the “Stock Repurchase Program”) to grant management the authority to repurchase shares of Class A Stock. In May and November 2019, the Board of Directors increased the buyback authorization by 1,212,759 and 1,000,000 shares of Class A Stock, respectively.

On April 16, 2019 and September 16, 2019, GAMCO repurchased 1.2 million and 70 thousand shares, respectively, of Class A Stock at $21.00 and $20.07 per share, respectively, in private transactions. For the years ended December 31, 2019 and 2018, outside of the private transactions, the Company repurchased 551,675 and 419,995 shares, respectively, at an average price per share of $18.99 and $25.25, respectively. At December 31, 2019, the total shares available under the Stock Repurchase Program to be repurchased in the future were 1,243,135. The Stock Repurchase Program is not subject to an expiration date.

Dividends

During 2019 and 2018, the Company declared dividends of $0.08 per share to class A and class B shareholders totaling $2.2 million and $2.3 million, respectively.

Shelf Registration

In April 2018, the SEC declared effective the Company’s “shelf” registration statement on Form S-3 giving the Company the flexibility to sell any combination of senior and subordinate debt securities, convertible debt securities, and equity securities (including common and preferred securities) up to a total amount of $500 million. The shelf is available through April 2021, at which time it may be renewed.