CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME UNAUDITED (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Comprehensive Income [Abstract]
Net income	$ 24,759us-gaap_ProfitLoss	$ 27,976us-gaap_ProfitLoss
Other comprehensive income, net of tax
Foreign currency translation	(42)	8
Net unrealized gains on securities available for sale, net of tax	(467)	(2,697)
Other comprehensive income	(509)	(2,689)
Comprehensive income	24,250	25,287
Less: Comprehensive income attributable to noncontrolling interests	17	(22)
Comprehensive income attributable to GAMCO Investors, Inc.	$ 24,267us-gaap_ComprehensiveIncomeNetOfTax	$ 25,265us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount of Net Income (Loss) attributable to noncontrolling interest.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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