Stockholders' Equity	3 Months Ended
Mar. 31, 2020
Stockholders' Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Shares outstanding were 27.7 million and 27.4 million on March 31, 2020 and December 31, 2019, 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 our common stock. A maximum of 7.5 million shares of Class A Stock have been reserved for issuance under the Plan by a committee of GBL’s board of directors (the “Board of Directors”) responsible for administering the Plan (“Compensation Committee”). 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 restricted stock awards (“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 June 30, 2019, 264,900 RSAs were issued at a grant price of $19.17 per RSA. On March 5, 2020, 392,700 RSAs were issued at a grant price of $14.31 per RSA. As of March 31, 2020 and December 31, 2019, there were 1,040,900 and 660,950, respectively, of these RSAs outstanding with weighted average grant prices per RSA of $19.54 and $22.67, respectively, and 10,000 of these stock options outstanding with an exercise price of $25.55. For the three months ended March 31, 2020 and 2019, the Company recognized stock-based compensation expense of $0.9 million and $0.6 million, respectively. The total compensation costs related to non-vested awards not yet recognized was approximately $13.6 million as of March 31, 2020. On April 1, 2019, the deferred cash compensation agreement (“DCCA”) with the CEO covering compensation from the fourth quarter of 2017 vested in accordance with the terms of the agreement 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 volume weighted average price (“VWAP”) on the vesting date ($20.7916) versus the VWAP over the fourth quarter of 2017 ($29.1875). On January 2, 2020, the DCCA with the CEO covering compensation from 2016 vested in accordance with the terms of the agreement 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). 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 2019, the Board of Directors increased the buyback authorization by 1,212,759 shares of Class A Stock. On March 18, 2020, the Board of Directors authorized an increase to purchase $30 million of its outstanding Class A Stock, which resulted in a modification in the form of the authorization from previously being stated in shares to being stated in dollars. For the three months ended March 31, 2020 and 2019, the Company repurchased 55,093 and 126,354 shares, respectively, at an average price per share of $17.16 and $20.15, respectively. At March 31, 2020, the total dollar amount available under the Stock Repurchase Program to be repurchased in the future was $30 million. The Stock Repurchase Program is not subject to an expiration date. On March 11, 2020, GAMCO commenced an offer to purchase up to $30 million in aggregate purchase price of its Class A Stock, pursuant to which holders of shares were invited to tender some or all of their shares at a price within the range of $15.00 to $17.00 per share, which would have enabled GAMCO to purchase for cash up to 2,000,000 shares of its Class A common stock (such offer, the “Offer”). The Offer which was due to expire on April 8, 2020, was terminated on March 18, 2020 as a result of the suspension of trading and market index conditions of the Offer not having been satisfied. As a result of this termination, no shares were purchased in the Offer and all shares previously tendered and not withdrawn were promptly returned to tendering holders. Dividends During the three months ended March 31, 2020 and 2019, the Company declared dividends of $0.02 per share to shareholders of Class A Stock and Class B Stock. 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. Stockholders’ Equity

Shares outstanding were 27.7 million and 27.4 million on March 31, 2020 and December 31, 2019, 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 our common stock. A maximum of 7.5 million shares of Class A Stock have been reserved for issuance under the Plan by a committee of GBL’s board of directors (the “Board of Directors”) responsible for administering the Plan (“Compensation Committee”). 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 restricted stock awards (“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 June 30, 2019, 264,900 RSAs were issued at a grant price of $19.17 per RSA. On March 5, 2020, 392,700 RSAs were issued at a grant price of $14.31 per RSA.

As of March 31, 2020 and December 31, 2019, there were 1,040,900 and 660,950, respectively, of these RSAs outstanding with weighted average grant prices per RSA of $19.54 and $22.67, respectively, and 10,000 of these stock options outstanding with an exercise price of $25.55.

For the three months ended March 31, 2020 and 2019, the Company recognized stock-based compensation expense of $0.9 million and $0.6 million, respectively.

The total compensation costs related to non-vested awards not yet recognized was approximately $13.6 million as of March 31, 2020.

On April 1, 2019, the deferred cash compensation agreement (“DCCA”) with the CEO covering compensation from the fourth quarter of 2017 vested in accordance with the terms of the agreement 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 volume weighted average price (“VWAP”) on the vesting date ($20.7916) versus the VWAP over the fourth quarter of 2017 ($29.1875). On January 2, 2020, the DCCA with the CEO covering compensation from 2016 vested in accordance with the terms of the agreement 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).

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 2019, the Board of Directors increased the buyback authorization by 1,212,759 shares of Class A Stock. On March 18, 2020, the Board of Directors authorized an increase to purchase $30 million of its outstanding Class A Stock, which resulted in a modification in the form of the authorization from previously being stated in shares to being stated in dollars.

For the three months ended March 31, 2020 and 2019, the Company repurchased 55,093 and 126,354 shares, respectively, at an average price per share of $17.16 and $20.15, respectively. At March 31, 2020, the total dollar amount available under the Stock Repurchase Program to be repurchased in the future was $30 million. The Stock Repurchase Program is not subject to an expiration date.

On March 11, 2020, GAMCO commenced an offer to purchase up to $30 million in aggregate purchase price of its Class A Stock, pursuant to which holders of shares were invited to tender some or all of their shares at a price within the range of $15.00 to $17.00 per share, which would have enabled GAMCO to purchase for cash up to 2,000,000 shares of its Class A common stock (such offer, the “Offer”). The Offer which was due to expire on April 8, 2020, was terminated on March 18, 2020 as a result of the suspension of trading and market index conditions of the Offer not having been satisfied. As a result of this termination, no shares were purchased in the Offer and all shares previously tendered and not withdrawn were promptly returned to tendering holders.

Dividends

During the three months ended March 31, 2020 and 2019, the Company declared dividends of $0.02 per share to shareholders of Class A Stock and Class B Stock.

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.