Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Jun. 30, 2013	Mar. 01, 2014 Class A [Member]	Mar. 01, 2014 Class B [Member]
Entity Information [Line Items]
Entity Registrant Name	GAMCO INVESTORS, INC. ET AL
Entity Central Index Key	0001060349
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding			6,649,564	19,379,452
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2013
Entity Public Float		$ 0