Calamos Asset Management (CLMS) 10-K 13 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Feb. 27, 2015
Entity Information [Line Items]
Entity Registrant Name	Calamos Asset Management, Inc. /DE/
Entity Central Index Key	1299033
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$241.40
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding			20,529,330
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding			100

CONSOLIDATED_STATEMENTS_OF_FIN

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$35,285	$39,078
Receivables:
Affiliates and affiliated funds	16,024	16,306
Customers	2,967	5,806
Investment securities	339,959	472,241
Partnership investments	143,723	46,425
Prepaid expenses	3,188	2,812
Deferred tax assets, net	9,194	10,165
Other current assets	2,508	2,283
Total current assets	552,848	595,116
Non-current assets:
Deferred tax assets, net	31,067	36,575
Goodwill	6,380	6,380
Property and equipment, net of accumulated depreciation and amortization ($61,145 at December 31, 2014 and $60,339 at December 31, 2013)	14,246	16,990
Other non-current assets	2,615	3,183
Total non-current assets	54,308	63,128
Total assets	607,156	658,244
Current liabilities:
Distribution fees payable	10,614	10,655
Accrued compensation and benefits	24,476	22,527
Current portion of long-term debt	0	46,160
Interest payable	1,386	2,729
Liabilities of partnership investments	10,117	12,378
Accrued expenses and other current liabilities	6,009	7,224
Total current liabilities	52,602	101,673
Non-current liabilities:
Long-term debt	45,955	45,955
Deferred rent	8,803	9,013
Other non-current liabilities	1,710	3,121
Total non-current liabilities	56,468	58,089
Total liabilities	109,070	159,762
Redeemable non-controlling interest in partnership investments	76,167	7,551
EQUITY
Additional paid-in capital	221,208	218,359
Retained earnings	89,311	86,115
Accumulated other comprehensive income	1,297	2,863
Treasury stock; 7,070,059 shares at December 31, 2014 and 5,220,330 shares at December 31, 2013	-107,129	-99,528
Calamos Asset Management, Inc. stockholders’ equity	204,937	208,056
Non-controlling interest in Calamos Investments LLC (Calamos Interests)	216,982	282,875
Total equity	421,919	490,931
Total liabilities and equity	607,156	658,244
Class A Common Stock
EQUITY
Common Stock	250	247
Class B Common Stock
EQUITY
Common Stock	$0	$0

CONSOLIDATED_STATEMENTS_OF_FIN1

CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Non-current assets:
Property and equipment, accumulated depreciation and amortization	$61,145	$60,339
EQUITY
Treasury stock (in shares)	7,070,059	5,220,330
Class A Common Stock
EQUITY
Common Stock, par value (in dollar per share)	$0.01	$0.01
Common Stock, authorized (in shares)	600,000,000	600,000,000
Common Stock, shares issued (in shares)	24,990,781	24,696,095
Common Stock, shares outstanding (in shares)	17,920,722	19,475,765
Class B Common Stock
EQUITY
Common Stock, par value (in dollar per share)	$0.01	$0.01
Common Stock, authorized (in shares)	1,000	1,000
Common Stock, shares issued (in shares)	100	100
Common Stock, shares outstanding (in shares)	100	100

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
REVENUES
Investment management fees	$198,539	$212,398	$255,823
Distribution and underwriting fees	49,764	54,068	67,816
Other	2,659	2,664	3,037
Total revenues	250,962	269,130	326,676
EXPENSES
Employee compensation and benefits	86,054	85,551	82,154
Distribution expenses	48,432	53,082	65,027
Marketing and sales promotion	16,128	15,728	19,503
General and administrative	39,158	36,883	40,188
Total operating expenses	189,772	191,244	206,872
Operating income	61,190	77,886	119,804
NON-OPERATING INCOME
Net interest expense	-4,509	-5,764	-5,632
Investment and other income	19,913	35,439	26,837
Total non-operating income	15,404	29,675	21,205
Income before income taxes	76,594	107,561	141,009
Income tax provision	5,787	6,262	12,568
Net income	70,807	101,299	128,441
Net income attributable to non-controlling interest in Calamos Investments LLC (Calamos Interests)	-54,336	-80,169	-108,813
Net income attributable to redeemable non-controlling interest in partnership investments	-2,941	-2,502	-1,436
Net income attributable to Calamos Asset Management, Inc.	$13,530	$18,628	$18,192
Earnings per share: (in dollars per share)
Basic	$0.74	$0.94	$0.89
Diluted	$0.71	$0.92	$0.88
Weighted average shares outstanding:
Basic	18,275,246	19,903,507	20,334,299
Diluted	18,989,281	20,351,603	20,745,922
Cash dividends declared per share	$0.55	$0.50	$0.41

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$70,807	$101,299	$128,441
Unrealized gains (losses) on available-for-sale securities:
Unrealized gains	3,173	39,630	19,027
Reclassification adjustment for realized gains included in net income	-12,012	-19,732	-20,512
Other comprehensive income (loss), before income tax provision (benefit)	-8,839	19,898	-1,485
Income tax provision (benefit) related to other comprehensive income (loss)	-920	2,114	-122
Other comprehensive income (loss), after income tax provision (benefit)	-7,919	17,784	-1,363
Comprehensive income	62,888	119,083	127,078
Comprehensive income attributable to non-controlling interest in Calamos Investments LLC (Calamos Interests)	-47,964	-94,358	-107,663
Comprehensive income attributable to redeemable non-controlling interest in partnership investments	-2,941	-2,502	-1,436
Comprehensive income attributable to Calamos Asset Management, Inc.	$11,983	$22,223	$17,979

CONSOLIDATED_STATEMENTS_OF_CHA

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $)	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Non-controlling Interest in Calamos Investments LLC (Calamos Interests)	Redeemable Non-controlling Interest in Partnership Investments
In Thousands, unless otherwise specified
Balance at Dec. 31, 2011	$415,760	$241	$214,102	$67,991	($527)	($95,215)	$229,168	$12,034
Increase (Decrease) in Stockholders' Equity
Net Income	127,005			18,192			108,813	1,436
Other comprehensive income	-1,363				-213		-1,150
Issuance of common stock		3	-3
Cumulative impact of changes in ownership of Calamos Investments LLC	-1,014		417	-5	3		-1,429
Compensation expense recognized under stock incentive plans	5,090		1,121				3,969
Dividend equivalent accrued under stock incentive plans	-529			-117			-412
Increase from purchases								6,942
Equity and tax distributions to non-controlling interests	-75,165						-75,165
Dividends declared	-8,347			-8,347
Balance at Dec. 31, 2012	461,437	244	215,637	77,714	-737	-95,215	263,794	20,412
Increase (Decrease) in Stockholders' Equity
Net Income	98,797			18,628			80,169	2,502
Other comprehensive income	17,784				3,595		14,189
Issuance of common stock		3	-3
Repurchase of common stock by Calamos Investments LLC	-13,196					-2,930	-10,266
Impact of the redemption of common stock from Calamos Investments LLC by Calamos Asset Management, Inc.			1,383			-1,383
Cumulative impact of changes in ownership of Calamos Investments LLC	-1,651		5		5		-1,661
Distributions to redeemable non-controlling interests in partnership investments								-15,363
Compensation expense recognized under stock incentive plans	7,025		1,558				5,467
Impact on non-controlling interests as a result of dividends paid to Calamos Investments LLC on repurchased common stock			-221				221
Dividend equivalent accrued under stock incentive plans	-1,122			-252			-870
Equity and tax distributions to non-controlling interests	-68,168						-68,168
Dividends declared	-9,975			-9,975
Balance at Dec. 31, 2013	490,931	247	218,359	86,115	2,863	-99,528	282,875	7,551
Increase (Decrease) in Stockholders' Equity
Net Income	67,866			13,530			54,336	2,941
Other comprehensive income	-7,919				-1,547		-6,372
Issuance of common stock		3	-3
Repurchase of common stock by Calamos Investments LLC	-22,470					-4,990	-17,480
Impact of the redemption of common stock from Calamos Investments LLC by Calamos Asset Management, Inc.			2,611			-2,611
Cumulative impact of changes in ownership of Calamos Investments LLC	-1,455		-297		-19		-1,139
Compensation expense recognized under stock incentive plans	6,633		1,473				5,160
Impact on non-controlling interests as a result of dividends paid to Calamos Investments LLC on repurchased common stock			-935				935
Dividend equivalent accrued under stock incentive plans	-1,097			-244			-853
Consolidation of Calamos Global Opportunities Fund LP								73,387
Liquidation of Calamos Arista Strategic Fund LP								-7,719
Increase from purchases								7
Equity and tax distributions to non-controlling interests	-100,480						-100,480
Dividends declared	-10,090			-10,090
Balance at Dec. 31, 2014	$421,919	$250	$221,208	$89,311	$1,297	($107,129)	$216,982	$76,167

CONSOLIDATED_STATEMENTS_OF_CHA1

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) (Class A Common Stock)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Class A Common Stock
Issuance of common stock (in shares)	294,686	310,080
Repurchase of common stock (in shares)	1,849,729	1,220,330
Redemption of common stock (in shares)	294,686	165,524

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of period	$39,078	$106,796	$102,166
Cash flows provided by operating activities:
Net income	70,807	101,299	128,441
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	2,575	2,686	4,462
Other depreciation and amortization	4,428	4,577	5,469
(Gain) loss on disposal of property and equipment	-111	203	106
Amortization of deferred rent	-210	-262	-148
Change in unrealized (gains) losses on investment securities, derivative assets, derivative liabilities and partnership investments	-1,836	5,117	-4,675
Net realized gains on sale of investment securities, derivative assets, derivative liabilities and partnership investments	-2,781	-17,701	-15,125
Change in deferred tax asset valuation allowance	-2,148	-4,952	1,900
Deferred taxes, net	9,601	11,351	8,335
Stock based compensation	6,633	7,025	5,090
Employee taxes paid on vesting under stock incentive plans	-1,500	-1,600	-916
Receivables:
Affiliates and affiliated funds, net	282	1,450	736
Customers	2,839	4,064	165
Other assets	-2,650	-4,420	-916
Increase (decrease) in liabilities:
Distribution fees payable	-41	-2,282	-2,923
Accrued compensation and benefits	1,949	-1,426	272
Accrued expenses and other liabilities	-5,129	-461	-502
Net cash provided by operating activities	82,708	104,668	129,771
Cash flows provided by (used in) investing activities:
Net additions to property and equipment	-1,531	-2,187	-1,816
Purchases of investment securities	-204,571	-621,760	-348,687
Proceeds from sale of investment securities	331,526	529,207	345,040
Net purchases of derivatives	0	-1,720	-13,412
Contributions to partnership investments	-35,005	-2,034	-19,435
Distributions from partnership investments	2,226	17,502	170
Net cash paid for acquisition, net of cash acquired	0	0	-3,392
Net cash provided by (used in) investing activities	92,645	-80,992	-41,532
Cash flows used in financing activities:
Repayment of long-term debt	-46,160	0	0
Deferred tax benefit (expense) on vesting under stock incentive plans	54	-55	-97
Repurchase of common stock by Calamos Investments LLC (1,849,729 at December 31, 2014, and 1,220,330 at December 31, 2013 Class A common shares)	-22,470	-13,196	0
Equity distributions paid to non-controlling interests (Calamos Interests)	-71,571	-28,010	-27,692
Tax distributions paid to non-controlling interests (Calamos Interests)	-28,909	-40,158	-47,473
Cash dividends paid to common stockholders	-10,090	-9,975	-8,347
Net cash used in financing activities	-179,146	-91,394	-83,609
Net increase (decrease) in cash and cash equivalents	-3,793	-67,718	4,630
Cash and cash equivalents at end of period	35,285	39,078	106,796
Cash paid (refunded) for:
Income taxes, net	-1,484	1,507	2,334
Interest	$5,954	$5,954	$5,954

CONSOLIDATED_STATEMENTS_OF_CAS1

CONSOLIDATED STATEMENTS OF CASH FLOWS - Parenthetical (USD $)	12 Months Ended
	Dec. 31, 2014
Liabilities of partnership investments	7,700,000
Class A Common Stock
Repurchase of common stock (in shares)	1,849,729

Organization_and_Description_o

Organization and Description of Business	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business
	Calamos Asset Management, Inc. (“CAM”) is a holding company and as of December 31, 2014 owned 22.2% of Calamos Investments LLC (“Calamos Investments”). CAM, together with Calamos Investments and Calamos Investments’ subsidiaries (the “Company”), operates the investment advisory and distribution services businesses reported within these consolidated financial statements. CAM operates and is the sole manager, and thus controls all of the business and affairs of Calamos Investments and, as a result of this control, consolidates the financial results of Calamos Investments with its own financial results. The remaining 77.8% ownership interest in Calamos Investments is held by Calamos Family Partners, Inc. (“CFP”), a Delaware corporation, and John P. Calamos, Sr. the Chairman, Chief Executive Officer and Global Co-Chief Investment Officer of CAM. CFP and John P. Calamos, Sr. (collectively “Calamos Interests”) ownership interest, in accordance with applicable rules, is reflected and referred to within these consolidated financial statements as “non-controlling interests in Calamos Investments LLC”.
	The Company primarily provides investment advisory services to individuals and institutional investors through a series of investment products that include open-end and closed-end funds ("funds”), an exchange traded fund, separate accounts, offshore funds and partnerships. The subsidiaries through which the Company provides these services include: Calamos Advisors LLC (“CAL”), a Delaware limited liability company and registered investment advisor; Calamos Financial Services LLC (“CFS”), a Delaware limited liability company and registered broker-dealer; Calamos Wealth Management LLC, a Delaware limited liability company and registered investment advisor; and Calamos Investments LLP (formerly known as Calamos International LLP), a United Kingdom limited liability partnership, registered investment advisor with the Financial Conduct Authority in the United Kingdom, and a global distributor of the offshore funds and Company products.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Basis of Presentation
	The consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”), which require the use of estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Management believes the accounting estimates are appropriate and reasonably stated; however, due to the inherent uncertainties in making estimates, actual amounts could differ from these estimates.
	Principles of Consolidation
	The Company consolidates investments in which the Company’s ownership exceeds 50% or in which the Company operates and controls the business and affairs of the entity or is deemed to be the primary beneficiary. In order to make this determination, an analysis is performed to determine if the investment in an affiliate or partnership is a variable interest entity ("VIE"). The Company has evaluated its investments in affiliates and partnerships and has concluded that they are not VIEs. With respect to partnership investments, the limited partners have no control of the business and affairs of the partnership, no substantive ability to dissolve (liquidate) the partnership, or otherwise remove the general partner (CAL and Calamos Investments) without cause or have other substantive rights.
	The consolidated financial statements include the financial statements of CAM, Calamos Investments, Calamos Investments’ wholly- and majority-owned subsidiaries, and the Company’s partnerships in which it owns a majority interest or in which it has operating control. The equity method of accounting is used for investments in which the Company has significant influence, but less than 50% ownership. All significant intercompany balances and transactions have been eliminated.
	The Calamos Interests’ combined 77.8% interest in Calamos Investments at December 31, 2014 and 2013, is represented as a non-controlling interest in Calamos Investments LLC in the Company’s consolidated financial statements. Non-controlling interest in Calamos Investments is derived by multiplying the historical equity of Calamos Investments by the Calamos Interests’ aggregate ownership percentage for the periods presented. Issuances and repurchases of CAM’s common stock may result in changes to CAM’s ownership percentage and to the non-controlling interests’ ownership percentage of Calamos Investments with resulting changes reflected in the consolidated statements of changes in equity. Income is allocated based on the average ownership interest during the period in which the income is earned.
	CAM owns certain assets to which common stockholders have exclusive economic rights. As of December 31, 2014, 2013 and 2012, these assets include cash, cash equivalents and investment securities of $79.3 million, $78.3 million and $67.0 million, net current and non-current deferred tax assets of $40.3 million, $46.7 million and $55.3 million, and net current income taxes receivable of $2.4 million, $2.3 million and $606,000, respectively, and a loan receivable from Calamos Investments of $21.0 million as of December 31, 2014, that are reported together with Calamos Investments’ consolidated assets in the consolidated statements of financial condition. Additionally, net income before income taxes, of $76.6 million, $107.6 million and $141.0 million, respectively, for the years ended December 31, 2014, 2013 and 2012, each included $3.6 million, $2.0 million and $230,000, respectively, of income on cash and cash equivalents and investment securities held solely by CAM. These portions of CAM’s income and expense are not affected by non-controlling interests.
	Calamos Investments, through a wholly owned subsidiary, is indirectly the general partner and controls the operations of Calamos Arista Strategic Fund LP (formerly Black Strategic Fund, LP), a U.S. feeder fund and Calamos Arista Strategic Fund Ltd, an offshore feeder fund both to Calamos Arista Strategic Master Fund LTD (formerly Black Strategic Master Fund Ltd.), a hedge fund in the Cayman Islands. As Calamos Investments is the general partner and controls the operations of Calamos Arista Strategic Fund LP and Calamos Arista Strategic Fund Ltd, the results of these partnerships and the master fund are included in the Company’s consolidated financial results. Calamos Arista Strategic Fund LP was liquidated on December 26, 2014. The partnership redemptions were completed subsequent to December 31, 2014, therefore, the amount due to non-controlling interest of $7.7 million related to this partnership investment is presented in liabilities of partnership investments in our consolidated statements of financial condition for the year ended December 31, 2014. Calamos Investments, through its wholly owned subsidiaries and affiliates, is indirectly the general partner and controls the operations of Calamos Global Opportunities Fund LP, for which it acquired a majority interest in the partnership during the second quarter of 2014. The results of this partnership are included in the Company's consolidated financial statements for the year ended December 31, 2014. The operations of Calamos International Growth Fund LP were controlled by CAL, the general partner. In December 2013, the limited partners of Calamos International Growth Fund LP redeemed all of their interests in the fund. As a result, the Company deconsolidated Calamos International Growth Fund LP and accounted for this partnership investment using the equity method as of December 31, 2013. Calamos International Growth Fund LP was dissolved on April 10, 2014. See Note 7, Partnership Investments, for more discussion regarding these funds.
	For the periods the partnerships are consolidated, the assets and liabilities of the partnerships are presented as partnership investments and liabilities of partnership investments, respectively, in the consolidated statements of financial condition. The net income for these partnerships are included in investment and other income in the consolidated statements of operations, and the change in partnership investments is included in contributions to or distributions from partnership investments in the consolidated statements of cash flows. The underlying assets and liabilities that are being consolidated are described in Note 7, Partnership Investments. The combined interests of all of the consolidated partnerships not owned by the Company and that are redeemable at the option of the holder, are presented as redeemable non-controlling interest in partnership investments in the Company’s consolidated financial statements for the periods those partnerships were consolidated.
	The Company holds non-controlling interests in certain other partnership investments that are included in partnership investments in the consolidated statements of financial condition. These other partnership investments are accounted for under the equity method.
	Reclassifications
	The Company changed the presentation of assets and liabilities of partnership investments from a net basis to a gross basis in the consolidated statements of financial condition. Amounts previously reported have been reclassified to conform to the current period's presentation.
	Cash and Cash Equivalents
	All highly liquid financial instruments with maturities of three months or less from date of purchase, consisting primarily of investments in insured money market accounts and money market funds, are considered cash equivalents.
	Receivables from Customers
	Receivables from customers represent balances arising from contractual investment advisory services provided to separate account customers and are recorded on an accrual basis. Provisions for bad debt expense during the years ended December 31, 2014, 2013, and 2012 and allowance for doubtful accounts as of December 31, 2014 and 2013, were not material.
	Investment Securities
	The Company carries its investment securities at fair value. For a majority of the Company’s investments, fair values are determined based upon quoted prices in active markets. If quoted market prices are not available, the Company uses matrix, model or other similar pricing methods to determine fair value. Investment securities transactions are recorded on a trade-date basis.
	Investment securities are classified as available-for-sale as the Company does not intend to trade these securities in the near term. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported, net of income tax, as a separate component of equity until realized. Realized gains and losses from the sale of available-for-sale securities are determined on a specific identification basis and are included in investment and other income in the consolidated statements of operations.
	Investment securities that are classified as trading securities are carried at fair value with all changes in the value of the securities going through current earnings. Therefore, both realized and unrealized gains and losses on these securities are included in investment and other income in the consolidated statements of operations.
	On a quarterly basis, the Company conducts reviews to assess whether an other-than-temporary impairment exists on its available-for-sale investment securities. Other-than-temporary declines in value may exist when the fair value of an investment security has been below the carrying value for an extended period of time. If an other-than-temporary decline in value is determined to exist, the unrealized investment loss, net of tax is recognized in the consolidated statements of operations in the period in which the other-than-temporary decline in value occurs, as well as an accompanying permanent adjustment to accumulated other comprehensive income. See Note 5, Investment Securities for more discussion related to the other-than-temporary impairment charges recorded in 2014 and 2013.
	Derivative Assets and Liabilities
	From time to time, the Company enters into derivative contracts to mitigate the negative impact that changes in security prices may have on the investment portfolio. The Company does not measure effectiveness or meet the criteria for hedge accounting and, therefore, records the changes in the fair value of these instruments in investment and other income in the consolidated statements of operations. The Company classifies derivatives as derivative assets and derivative liabilities in the consolidated statements of financial condition.
	Goodwill
	The Company’s goodwill represents the future economic benefits arising from Calamos Investments’ acquisition of Black Capital, LLC (“Black Capital”) that are not individually identified and separately recognized. Goodwill is assessed for impairment at the reporting unit level, Calamos Investments, at least annually, or whenever events or circumstances occur indicating that an impairment may have occurred. The goodwill impairment test is a two-step process. The first step requires the Company to estimate the fair value of its reporting unit and compare the fair value to the reporting unit’s carrying amount. If the fair value exceeds the carrying amount, the goodwill is not considered impaired. To the extent the reporting unit’s carrying amount exceeds its fair value, the reporting unit’s goodwill may be impaired and the second step of the impairment test must be performed. The second step involves assigning the reporting unit’s fair value to all of its recognized and unrecognized assets and liabilities as if the reporting unit had been acquired in a business combination in order to determine the implied fair value of the reporting unit’s goodwill. The implied fair value of the reporting unit’s goodwill is then compared to the carrying amount of goodwill to quantify an impairment loss, if any, which would equal the excess of the carrying amount of goodwill over the goodwill’s implied fair value. No impairment has been recorded for the years ended December 31, 2014, 2013 and 2012. See Note 3, Acquisition for more discussion related to the acquisition of Black Capital.
	Property and Equipment
	Property and equipment are recorded at cost less accumulated depreciation and amortization. Depreciation and amortization is provided on a straight-line basis over the estimated useful lives of the assets, ranging from three to twenty years. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining term of the lease, ranging from five to twenty years.
	Property and equipment are reviewed for impairment when there is an indication that the carrying amount of an asset may not be recoverable. Carrying values are not recoverable when the undiscounted cash flows estimated to be generated by the assets are less than their carrying value. When an asset is determined to not be recoverable, the impairment loss is measured based on the excess, if any, of the carrying value of the asset over its respective fair value. Fair value is determined by discounted cash flows models, appraisals or other applicable methods.
	Internally Developed Software
	Certain internal and external development costs incurred in connection with developing or obtaining software for internal use are capitalized. These capitalized costs are included in property and equipment, net in the consolidated statements of financial condition and are amortized using the straight-line method over their estimated useful lives, ranging from three to five years. On an annual basis, the Company conducts reviews to assess the functionality and remaining useful lives of the capitalized software. Impairments of these assets, if any, are recognized in the consolidated statements of operations in the period in which the impairment occurs. No impairment for internally developed software has been recorded for the year ended December 31, 2014. For the years ended December 31, 2013 and 2012, the Company recorded impairment for its internally developed software totaling $199,000 and $107,000, respectively.
	Restricted Cash
	The Company has a $429,000 security deposit that is restricted from the Company’s general corporate use and is being reported in other non-current assets in the consolidated statements of financial condition.
	Treasury Stock
	During the years ended December 31, 2014 and 2013, Calamos Investments repurchased 1,849,729 and 1,220,330, respectively, shares of Class A common stock, at an average purchase price of $12.15 and $10.81, respectively, and a total cost of $22.5 million and $13.2 million, respectively, under its share repurchase programs.
	Calamos Investments completed a share repurchase program of 3 million shares of the Company's outstanding Class A Common Stock for a total cost of $34.8 million on June 13, 2014. The program was implemented primarily to manage the dilution from share issuances under the Company’s incentive compensation plan. During the year ended December 31, 2014, Calamos Investments repurchased 1,779,670 shares of Class A common stock, at an average purchase price of $12.13 and a total cost of $21.6 million under this repurchase program. On November 13, 2014, the Company announced a repurchase of up to an additional 3 million shares of the Company's outstanding Class A Common Stock. During the year ended December 31, 2014, Calamos Investments repurchased 70,059 shares of Class A common stock, at an average purchase price of $12.54 and a total cost of $879,000 under this repurchase program.
	As Calamos Investments is consolidated with CAM, the repurchased shares are reported as treasury shares.  As such, CAM’s 22.2% ownership interest in these shares as of December 31, 2014 and 2013, totaling $5.0 million and $2.9 million, respectively, is reported in treasury stock, with Calamos Interests’ 77.8% ownership interest in these shares totaling $17.5 million and $10.3 million, respectively, reported in non-controlling interest in the consolidated statements of financial condition. The total shares repurchased are not included in the calculation of basic and diluted earnings per share in accordance with GAAP.
	During 2014 and 2013, CAM redeemed 294,686 and 165,524, respectively, Class A common shares from Calamos Investments for a value of $3.4 million and $1.8 million, respectively, which represents the fair value of the shares on the date of redemption. As Calamos Investments is consolidated with CAM, the impact of the distribution reflecting the non-controlling interest is $2.6 million and $1.4 million, respectively.
	For the years ended December 31, 2014 and 2013, dividends on shares held by Calamos Investments totaled $1.2 million and $284,000, respectively. The payment of these dividends increased Calamos Investments' equity resulting in a $935,000 and $221,000, respectively, adjustment from additional paid in capital to non-controlling interest in Calamos Investments LLC, in the consolidated statement of changes in equity. This adjustment represents Calamos Interests' ownership interest in those dividend payments.
	Compensation Plans
	The Company has an incentive stock plan that provides for certain employees of the Company to receive stock based compensation in the form of restricted stock units (“RSUs”) and stock options. RSUs are convertible on a one-for-one basis into shares of the Company’s common stock. Stock option awards are based on shares of the Company’s common stock. The Company estimates the fair value of the options as of the grant date using the Black-Scholes option-pricing model. Stock based compensation expense is recognized based on the grant-date fair value of the award. The Company records compensation expense on a straight-line basis over the service period.
	Revenue Recognition
	The Company earns investment management fees by providing services pursuant to the terms of the underlying advisory contract. Fees are based on a contractual investment advisory fee applied to the assets in each portfolio. Any fees collected in advance are deferred and recognized over the period earned. Performance-based advisory fees from certain separate accounts are recognized annually upon completion of the contract year and based upon either (1) the difference between the investment returns on a client’s portfolio compared to a benchmark index or (2) the absolute percentage of gain in the client’s account. Performance-based advisory fees from the open-end funds are recognized monthly when earned and are based upon the differences between the investment returns of the respective fund compared to a benchmark index.
	Distribution and underwriting fees consist primarily of Rule 12b-1 distribution and/or service fees from the open-end funds, contingent deferred sales charges on the redemption of open-end fund shares and sales charges earned on open-end funds. Distribution service fees are accrued monthly as services are performed and are based on the average daily assets of the open-end funds. Contingent deferred sales charges are recorded on a trade-date basis when earned, and sales charges are recorded on the settlement date.
	Net Interest Expense
	Net interest expense represents interest expense incurred on debt net of interest income generated from cash and cash equivalents. Interest income is recognized when earned, and interest expense is recorded when incurred.
	Investment and Other Income
	Investment and other income is primarily comprised of: realized gains (losses) from all investment securities and partnership investments; unrealized gains (losses) on trading securities and partnership investments; realized and unrealized gains (losses) on derivatives; gains (losses) on foreign currency translation; and dividend income. Dividend income is recognized on the ex-dividend date.
	Foreign Currency
	Foreign currency balances are revalued into U.S. dollars, which is the functional currency of the Company, at prevailing exchange rates on the reporting date. Revenues earned and expenses incurred in foreign currency are revalued at average exchange rates during the reporting period. Gains and losses arising from the revaluation of account balances denominated in foreign currencies are recognized in investment and other income in the consolidated statements of operations.
	Income Taxes
	Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the temporary differences between the financial statement carrying amount of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. During 2014 and 2013, the Company recorded valuation allowance adjustments to reduce its deferred income tax assets to an amount that is more likely than not to be realized based on available evidence at the time estimates are made.
	Determining a valuation allowance requires management to make significant judgments and assumptions. In determining a valuation allowance the Company uses historical and forecasted future realized and unrealized gains and losses on its investment, ongoing tax planning strategies, and forecasts of future taxable income. Each quarter the Company re-evaluates its estimates related to its valuation allowance, including its assumptions about future taxable income. The Company’s capital loss carryforward is used against realized gains on its investment, derivative assets, derivative liabilities and partnership investments, using its tax harvesting strategies. See Note 16, Income Taxes for more discussion related to the deferred tax valuation allowance.
	Future interest or penalties related to uncertain income tax positions are recognized in income tax provision when determined. The Company did not record any accrued interest or penalties related to uncertain tax positions through December 31, 2014.
	Advertising Costs
	Advertising costs are expensed as incurred and are included in marketing and sales promotion expenses in the consolidated statements of operations. For the years ended December 31, 2014, 2013 and 2012, advertising costs were $3.8 million, $3.7 million and $5.4 million, respectively.
	Earnings Per Share
	Basic earnings per share is computed by dividing net income attributable to CAM by the weighted average number of shares of Class A and Class B common stock outstanding during each year. Shares issued or repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted earnings per share reflects the potential dilution that would occur if RSUs and stock options granted to participants of the Company incentive compensation plan were exercised and if the Calamos Interests exchanged all of their ownership interest in Calamos Investments and their Class B common stock for shares of Class A common stock. Diluted shares which result in anti-dilution are excluded from the diluted earnings per share calculation and are detailed in Note 17, Earnings Per Share.

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisition	Acquisition
	On August 31, 2012, Calamos Investments acquired Black Capital, a long/short equity investment firm located in New York City for a total purchase price of $6.8 million. The acquisition expanded the Company’s existing capabilities in alternative strategies with an investment team that manages a long/short equity hedge fund. At closing, $3.4 million was paid to the seller with the remaining balance due in two equal installments, payable 18 and 36 months thereafter. There are no performance contingencies associated with the remaining installment payments. This future obligation is reported in other current liabilities.
	The excess of the purchase price over the fair value of identifiable tangible and intangible assets acquired resulted in the recognition of $6.4 million of goodwill. Acquisition-related expenses for professional services were expensed as incurred, and recorded in general and administrative expenses. The Company has not presented pro-forma combined results of operations for this acquisition, as the information was immaterial to the Company’s consolidated financial statements. The amount of revenue earned during 2012 as a result of the acquisition was immaterial.

RelatedParty_Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions
	CAL provides investment management and portfolio accounting services to the open-end funds and the closed-end funds. CFS acts as the sole distributor of the U.S. open-end funds. Calamos Investments LLP is the sole global distributor of the offshore funds. The Company earns management, distribution and portfolio accounting fees for these services that are accrued and settled monthly. The table below summarizes the total fees earned from affiliates identified above during the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013		2012
	Investment management fees from:
	Open-end funds	$	119,898		$	124,875	$	158,040
	Closed-end funds	57,911			53,981		49,842
	Totals	$	177,809		$	178,856	$	207,882
	Distribution fees from open-end funds	$	48,942		$	53,143	$	66,604
	Portfolio accounting fees from:
	Open-end funds	$	1,756		$	1,810	$	2,239
	Closed-end funds	727			679		623
	Totals	$	2,483		$	2,489	$	2,862
	In September 2012, CAL began providing investment management services to Calamos Arista Strategic Master Fund LTD, a hedge fund in the Cayman Islands. Calamos Arista Strategic Fund LP was a newly consolidated partnership and U.S. feeder fund to Calamos Arista Strategic Master Fund LTD.  For the years ended December 31, 2014, 2013 and 2012, management and incentive fees for those services were $58,000, $85,000 and $16,000, respectively.
	Calamos Investments is party to a lease with 1111 Warrenville Road LLC, a subsidiary of Calamos Property Holdings LLC (“CPH”). In January 2011, Calamos Investments and 1111 Warrenville Road LLC amended the lease in order to extend the term for two years with automatic one year renewals and to increase the base rent accordingly. Rent under the lease commenced in August 2005 and will end on December 31, 2015. For the years ended December 31, 2014, 2013 and 2012 annual base rent and operating expense payments were $774,000, $712,000 and $809,000, respectively.
	Calamos Investments is party to a 20-year lease with 2020 Calamos Court LLC, a subsidiary of CPH, with respect to the corporate headquarters constructed for the Company’s occupancy. Rent under the lease commenced in April 2005 and will end on May 31, 2025. For the years ended December 31, 2014, 2013 and 2012, annual base rent payments were $3.7 million, $3.6 million and $3.5 million, respectively. Annual base rent payments increase by 3% annually for the remaining term of the lease. Calamos Investments may not terminate the lease unless a casualty, condemnation or temporary government taking affects all or a substantial portion of the leased premises. 2020 Calamos Court LLC may only terminate the lease upon specified events of default, which are subject to applicable grace periods.
	Calamos Investments is party to an agreement with Primacy Business Center LLC (“Primacy”), a subsidiary of CFP, where office space at the Company’s corporate headquarters is subleased to Primacy. The lease expires December 31, 2015, but automatically extends annually. Calamos Investments recognized sublease rental income of $277,000 for each of the years ended December 31, 2014, 2013 and 2012, which is classified as other income and included in investment and other income in the consolidated statements of operations.
	Calamos Investments is party to a 20-year lease with 2020 Calamos Court Annex LLC, a subsidiary of CPH, with respect to the cafeteria in the Company’s corporate headquarters. Rent under the lease commenced in December 2005 and will end on May 31, 2025. For the years ended December 31, 2014, 2013 and 2012, annual base rent and operating expense payments were $321,000, $300,000 and $289,000, respectively. Annual base rent payments increase by 3% annually for the remaining term of the lease.
	Calamos Investments is party to an agreement with CF Restaurant Enterprises LLC (“CFRE”), a subsidiary of CFP, where CFRE provides food and beverage services to Calamos Investments. Calamos Investments guarantees minimum daily revenues and CFRE agrees that certain quantities and combinations of food and beverage will be available at a predetermined price. For the years ended December 31, 2014, 2013 and 2012, Calamos Investments incurred expenses of $940,000, $956,000 and $976,000, respectively.
	Calamos Investments is party to a 7.5 year lease with CityGate Centre I LLC, a subsidiary of CPH, with respect to office space. Rent payments under the lease commenced in May 2008 and will end on April 30, 2015. For the years ended December 31, 2014, 2013 and 2012, annual base rent and operating expense payments were $990,000, $943,000 and $922,000, respectively. Annual base rent payments increase by 2.5% annually.
	Calamos Investments headquarter campus is owned and operated by CFP, CPH and their subsidiaries (collectively, “CityGate Centre”) and is utilized by the Company to promote its business and brand awareness both in the local community and with its visiting strategic clients. CityGate Centre offers amenities such as hotel accommodations, restaurants and event planning services.  For the years ended December 31, 2014, 2013 and 2012, Calamos Investments had expense payments of $530,000, $533,000 and $632,000, respectively, related to these services.
	JPC Falcon 1109 LLC (“JPC Falcon”) is an affiliated company controlled by a principal of the Company. CAL was party to a non-exclusive lease agreement with JPC Falcon, dated April 26, 2012, whereby CAL had use of an airplane owned by JPC Falcon. Under the agreement, CAL had use of the airplane for business travel and agreed to pay for the airplane use, along with other related expenses. There were no expenses related to this agreement in 2014 and 2013. For the year ended December 31, 2012, expenses related to this agreement were $589,000. The agreement expired on April 26, 2013.
	Dragon Leasing Corporation (“Dragon”) is an affiliated company controlled by a principal of the Company. CFP, CPH and Dragon have each entered into agreements with CAM, whereby the parties provide to each other certain services and resources, including furnishing office space and equipment, providing insurance coverage, overseeing the administration of their businesses and providing personnel to perform certain management and administrative services. These agreements have a term of one year and are renewable annually. The agreements are terminable on 30 days' notice by either party. In accordance with the terms of the agreements, the parties have agreed to pay each other an amount equal to the direct out-of-pocket expenses paid or incurred plus an allocation of indirect expenses, such as employee compensation and benefits.
	The following table summarizes fees that have been recorded as expense allocations during the twelve months ended and the net receivable balance as of December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013		2012
	Expense allocated from the Company to CPH	$	590		$	556	$	606
	Expense allocated from the Company to CFP	243			236		245
	Expense allocated from the Company to Dragon	16			16		18
	Total expenses allocated from the Company to affiliates	849			808		869
	Expense allocated from CPH and CFP to the Company	173			151		196
	Net expense allocated from the Company to affiliates	$	676		$	657	$	673
	Net receivable for management services from CPH	$	40		$	43	$	1
	Net receivable (payable) for management services from CFP	$	(11	)	$	9	$	4
	Net receivable for management services from Dragon	$	1		$	1	$	41
	Other receivables as a result of Black Capital purchase	$	—		$	—	$	38
	As a result of the control exercised by CFP, none of our agreements with CFP and other companies controlled by them are deemed to be negotiated on “arm’s length” terms. However, while not mandated, to date, any such agreements since the Company's initial public offering have been approved in accordance with the Conflict of Interests Policy contained in the Company's Second Amended and Restated Certificate of Incorporation.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Investment Securities	Investment Securities
	The following table provides a summary of investment securities as of December 31, 2014 and 2013:
	(in thousands)
	December 31, 2014		Cost			Unrealized Gains			Unrealized Losses				Fair Value
	Available-for-sale securities:
	Funds
	Equity
	Global Growth		$	142,610		$	5,275		$	(1,872	)		$	146,013
	U.S. Growth		64,526			3,194			(410		)		67,310
	Value		9,979			286			(171		)		10,094
	Alternative		40,752			1,283			(4		)		42,031
	Fixed Income/High Yield		17,596			1			(423		)		17,174
	Convertible		10,163			15			(1		)		10,177
	Multi-Strategy		1,494			198			(9		)		1,683
	Total Funds		287,120			10,252			(2,890		)		294,482
	Common stock		136			125			—				261
	Total available-for-sale securities		$	287,256		$	10,377		$	(2,890	)		$	294,743
	Trading securities:
	Funds
	Equity
	U.S. Growth		$	52,147		$	33		$	(6,964	)		$	45,216
	Total investment securities												$	339,959
	(in thousands)
	December 31, 2013		Cost			Unrealized Gains			Unrealized Losses				Fair Value
	Available-for-sale securities:
	Funds
	Equity
	Global Growth		$	214,811		$	11,097		$	(15	)		$	225,893
	U.S. Growth		55,109			2,971			(436		)		57,644
	Value		9,886			315			(243		)		9,958
	Alternative		35,436			2,000			—				37,436
	Fixed Income/High Yield		98,834			429			(4		)		99,259
	Convertible		142			3			—				145
	Multi-Strategy		1,272			130			(2		)		1,400
	Total Funds		415,490			16,945			(700		)		431,735
	Common stock		133			80			—				213
	Total available-for-sale securities		$	415,623		$	17,025		$	(700	)		$	431,948
	Trading securities:
	Funds
	Equity
	U.S. Growth		$	48,539		$	320		$	(8,566	)		$	40,293
	Total investment securities												$	472,241
	Of the $339.7 million and $472.0 million investments in Funds at December 31, 2014 and 2013, respectively, $339.7 million and $427.6 million, respectively, were invested in affiliated funds and accounts that are separately managed.
	The aggregate fair value of available-for-sale investment securities that were in an unrealized loss position at December 31, 2014 and 2013 was $98.1 million and $14.0 million, respectively. As of December 31, 2014 and 2013, the Company had no investment securities that had been in a continuous loss position for 12 months or longer.
	The Company recorded other-than-temporary impairment charges of $667,000 and $7.5 million, respectively, on certain available-for-sale securities with unrealized losses during 2014 and 2013. The other-than-temporary impairment charges were reported in non-operating income, in the consolidated statements of operations.
	As of December 31, 2014, the Company believes that the remaining $2.9 million in unrealized losses on certain available-for-sale securities are only temporary in nature, as these losses are a result of short-term declines in the net asset value of the funds. Further, the Company has the intent and ability to hold these securities for a period of time sufficient to allow for recovery of the market value. The Company also considered current market conditions and the nature of the securities held when determining the recoverability of those securities market value.
	The following table provides a summary of changes in investment securities for the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013			2012
	Available-for-sale securities:
	Proceeds from sales	$	293,662		$	524,968		$	344,911
	Gross realized gains on sales	$	11,024		$	25,882		$	28,587
	Trading securities:
	Unrealized gains (losses)	$	1,315		$	(8,813	)	$	94
	The table below summarizes the tax provision (benefit) on unrealized gains and gains reclassified out of accumulated other comprehensive income (loss) on available-for-sale securities for the years ended December 31, 2014, 2013 and 2012:
		2014										2013									2012
	(in thousands)	Before-Tax Amount			Tax Provision (Benefit)			After-Tax				Before-Tax Amount			Tax Provision (Benefit)			After-Tax			Before-Tax Amount			Tax Provision (Benefit)			After-Tax
								Amount										Amount									Amount
	Available-for-sale securities:
	Changes in unrealized gains	$	3,173		$	404		$	2,769			$	39,630		$	3,793		$	35,837		$	19,027		$	1,554		$	17,473
	Reclassification adjustment for realized gains included in income	(12,012		)	(1,324		)	(10,688		)		(19,732		)	(1,679		)	(18,053		)	(20,512		)	(1,676		)	(18,836		)
	Other comprehensive income (loss)	$	(8,839	)	$	(920	)	$	(7,919	)		$	19,898		$	2,114		$	17,784		$	(1,485	)	$	(122	)	$	(1,363	)
	Reclassification of realized gains out of accumulated other comprehensive income (loss) are reported in non-operating income, in investment income, in the consolidated statement of operations.  See Note 15, Non-Operating Income.

Derivative_Assets_and_Liabilit

Derivative Assets and Liabilities	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Assets and Liabilities	Derivative Assets and Liabilities
	The Company used exchange-traded option contracts as an economic hedge of price changes in its investment securities portfolio in order to reduce the volatility equity markets had on the fair value of the Company's corporate investment portfolio and that could have resulted in realized or unrealized losses during the third and fourth quarters of 2014. The Company's investment securities, totaling $340.0 million at December 31, 2014, consist primarily of positions in several Calamos equity and fixed income funds. The equity price risk in the investment portfolio was hedged using exchange-traded option contracts that correlate most closely with the change in value of the portfolio being hedged. The use of these option contracts was part of a hedge overlay strategy to minimize downside risk in the hedged portfolio. The Company may adjust its hedge position in response to movement and volatility in prices and changes in the composition of the hedged portfolio, but generally is not actively buying and selling contracts.
	The Company has elected not to offset its derivative assets with its derivative liabilities even if a right of offset exists. When applicable, the fair value of option contracts is reported on a gross basis in derivative assets and derivative liabilities in the consolidated statements of financial condition. Net gains and losses on these contracts are reported in investment and other income in the consolidated statements of operations with net losses of $1.8 million, $1.9 million and $10.5 million for the years ended December 31, 2014, 2013 and 2012, respectively. The Company used these derivatives for risk management purposes but has not designated the contracts as hedges for accounting purposes. The Company had no derivative instruments outstanding as of December 31, 2014 and 2013.

Partnership_Investments

Partnership Investments	12 Months Ended
	Dec. 31, 2014
Partnership Investments [Abstract]
Partnership Investments	Partnership Investments
	Presented below are the underlying assets and liabilities of the partnerships that the Company reports on a consolidated basis, as well as partnership investments that the Company accounts for under the equity method. These investments are presented as partnership investments and liabilities of partnership investments, respectively, in its consolidated statements of financial condition as of December 31, 2014 and 2013.
	(in thousands)	2014			2013
	Consolidated partnerships:
	Assets
	Securities owned	$	103,079		$	29,149
	Cash and cash equivalents	39,205			12,208
	Receivables for securities sold	—			1,076
	Other current assets	1,188			30
	Exchange-traded option contracts	201			150
	Total assets of consolidated partnerships	$	143,673		$	42,613
	Liabilities
	Securities sold not yet purchased	$	—		$	(10,670	)
	Payables for securities purchased	(2,256		)	(1,576		)
	Due to non-controlling interest in partnership investments	(7,719		)	—
	Accrued expenses and other current liabilities	(142		)	(76		)
	Exchange-traded options contracts	—			(56		)
	Total liabilities of consolidated partnerships	$	(10,117	)	$	(12,378	)
	Equity method investment in partnerships	$	50		$	3,812
	Profits and losses are allocated to the general partner and limited partners in proportion to their ownership interests at the beginning of each month. Partners' admissions, additional contributions and withdrawals are permitted on a monthly basis.
	During 2012, the Company formed a wholly owned limited liability company, which became the general partner of Calamos Arista Strategic Fund LP, a U.S. feeder fund and Calamos Arista Strategic Fund Ltd, an offshore feeder fund that both invested in Calamos Arista Strategic Master Fund Ltd. As the general partner of Calamos Arista Strategic Fund LP, the Company had certain rights, including rights to any incentive fees that may have been earned from the net profits of the master fund. As a result of the Company’s control and majority ownership interest, the Company consolidated this partnership. This investment is presented as a consolidated partnership for the years ended December 31, 2014 and 2013. Calamos Arista Strategic Fund LP was liquidated on December 26, 2014, and as of December 31, 2014, the net assets were $30.8 million. The partnership redemptions were completed subsequent to December 31, 2014.
	The Company was a general partner of Calamos International Growth Fund LP. In December 2013, the limited partners of Calamos International Growth Fund LP redeemed all of their interests in the fund. As a result, the Company accounted for this partnership investment using the equity method as of December 31, 2013. Calamos International Growth Fund LP was dissolved on April 10, 2014. This investment is presented as an equity method investment in partnerships as of December 31, 2013, in the table above.
	The Company held a non-controlling interest in Calamos Global Opportunities Fund LP during 2013 and early 2014 and therefore, accounted for this investment using the equity method. During the second quarter of 2014, Calamos Investments, through its wholly owned subsidiaries and affiliates, acquired a majority interest in Calamos Global Opportunities Fund LP. During 2013, the Company redeemed $18.7 million of its interest in Calamos Global Opportunities Fund LP for proceeds of $20.0 million, resulting in a realized gain of $1.3 million.This investment is presented as a consolidated partnership as of the year ended December 31, 2014, and an equity method investment as of December 31, 2013, in the table above.
	As of December 31, 2014 and 2013, the Company held non-controlling interests in another partnership and therefore, accounted for this investment using the equity method. This investment is presented as an equity method investment in partnerships in the table above.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	The Company utilizes a three-tier fair value hierarchy which prioritizes the inputs used in measuring fair value as follows: Level 1 — observable inputs such as quoted prices for identical assets and liabilities in active markets; Level 2 — inputs, other than the quoted prices in active markets, that are observable either directly or indirectly (including quoted prices of similar securities, interest rates, credit risk, fair value adjustments to quoted foreign securities, etc.); and Level 3 — unobservable inputs in which there is little or no market data, and require the reporting entity to develop its own assumptions. For each period presented, the Company did not have any assets or liabilities measured at fair value using Level 3 measurements. Transfers between levels are measured at the end of the reporting period. The Company had no transfers between levels during the years ended December 31, 2014 and 2013.
	Investments are presented in the consolidated financial statements at fair value in accordance with GAAP. Investments in open-end funds are stated at fair value based on end of day published net asset values of shares owned by the Company. The fair value of investments in open-end funds was $297.0 million and $450.4 million at the end of December 31, 2014 and 2013, respectively. There are no unfunded commitments related to these investments. These investments may be redeemed daily with a redemption notice period of up to seven days. Investments in securities traded on a national securities exchange are stated at the last reported sales price on the day of valuation. Other securities, including derivatives, traded in the over-the-counter market and listed securities for which no sale was reported on that date are stated at the last quoted bid price. However, short sales positions and call options written are reported at the last quoted asked price. Convertible bonds, fixed income securities and other securities for which quotations are not readily available are valued at fair value based on observable inputs such as market prices for similar instruments as validated by third party pricing agencies and the Company’s prime broker. Debt securities are valued based upon evaluated prices received from an independent pricing service or from a dealer or broker who makes markets in such securities. Pricing services utilize various observable market data and as such, debt securities are generally categorized as Level 2.
	The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2014 and 2013. Foreign currency contracts are carried in the Company's partnership investments and are presented on a net basis where the right of offset exists, and had no impact for either period presented.
					Fair Value Measurements Using
	(in thousands)	December 31, 2014			Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)			Significant Other Observable Inputs (Level 2)
	Description
	Cash and cash equivalents
	Money market funds	$	1,209		$	1,209		$	—
	Investment securities (Note 5)
	Funds
	Equity
	Global Growth	146,013			146,013			—
	U.S. Growth	112,526			112,526			—
	Value	12,218			12,218			—
	Alternative	42,031			42,031			—
	Fixed Income/High Yield	17,174			12,174			5,000
	Convertible	11,021			11,021			—
	Multi-Strategy	1,683			1,683			—
	Total Funds	342,666			337,666			5,000
	Common stock	261			261			—
	Investment securities	342,927			337,927			5,000
	Securities and derivatives owned by partnership investments (Note 7)
	Common stocks	51,403			26,237			25,166
	Preferred stocks	5,736			2,281			3,455
	Convertible bonds	41,119			—			41,119
	Corporate bonds	4,821			—			4,821
	Foreign currency	513			513			—
	Money market funds	37,060			7,851			29,209
	Exchange-traded put option contracts	201			201			—
		140,853			37,083			103,770
	Securities sold but not yet purchased (Note 5)
	Common stocks	(2,968		)	(2,968		)	—
	Total	$	482,021		$	373,251		$	108,770
					Fair Value Measurements Using
	(in thousands)	December 31, 2013			Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs
					and Liabilities			(Level 2)
	Description				(Level 1)
	Cash and cash equivalents
	Money market funds	$	1,752		$	1,752		—
	Investment securities (Note 5)
	Funds
	Equity
	Global Growth	225,892			225,892			—
	U.S. Growth	97,936			97,936			—
	Value	9,959			9,959			—
	Alternative	37,436			37,436			—
	Fixed Income/High Yield	99,260			99,260			—
	Convertible	145			145			—
	Multi-Strategy	1,400			1,400			—
	Total Funds	472,028			472,028			—
	Common stock	213			213			—
	Investment securities	472,241			472,241			—
	Securities and derivatives owned by partnership investments (Note 7)
	Common stocks	29,149			29,149			—
	Exchange-traded put option contracts	150			150			—
		29,299			29,299			—
	Securities sold but not yet purchased by partnership investments (Note 7)
	Common stocks	(10,185		)	(10,185		)	—
	Exchange-traded funds	(485		)	(485		)	—
	Exchange-traded call option contracts	(56		)	(56		)	—
		(10,726		)	(10,726		)	—
	Total	$	492,566		$	492,566		$	—
	The fair value of the Company’s long-term debt, which has a total carrying value of $46.0 million and $92.1 million at December 31, 2014 and 2013, was $54.2 million and $104.4 million, respectively. During the third quarter of 2014, $46.2 million of senior notes outstanding were repaid. The fair value of the Company’s payment obligation, which has a carrying value of $1.7 million and $3.4 million at December 31, 2014 and 2013, was $1.7 million and $3.3 million, respectively. This obligation, which is associated with the Company's purchase of Black Capital in 2012, is reported in other current liabilities in the consolidated statements of financial condition. These fair value estimates are calculated using discounted cash flows based on the Company’s incremental borrowing rates and market inputs for similar bonds for the debt, and the treasury yield curve plus market spread for the payment obligation. The fair values of the debt and payment obligation are based on Level 2 inputs within the fair value hierarchy.
The carrying value of all other financial instruments approximates fair value due to the short maturities of these financial instruments.

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment
	As of December 31, 2014 and 2013, property and equipment and related accumulated depreciation were as follows:
	(in thousands)	2014			2013
	Property and equipment:
	Furniture, fixtures and equipment	$	25,421		$	27,617
	Leasehold improvements	32,062			32,062
	Computer software	17,908			17,650
	Total costs	75,391			77,329
	Accumulated depreciation and amortization	(61,145		)	(60,339		)
	Property and equipment, net	$	14,246		$	16,990
	Computer software includes both internally developed software and software purchased.

Loans_Payable

Loans Payable	12 Months Ended
	Dec. 31, 2014
Loans Payable [Abstract]
Loans Payable	Loans Payable
	The Company has access to margin loans for the settlement of call options, as well as an additional source of liquidity. The interest rate that can be charged on margin loans is 1.5% per annum, based on the brokerage firm’s lending rate. These loans are due on demand. The Company can borrow up to 70% of its marginable securities on deposit with its brokerage firm. The Company had no margin loan balances outstanding at December 31, 2014 and 2013.

Debt

Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt	Debt
	In July 2007, Calamos Investments completed a private debt offering of $375 million aggregate principal senior unsecured notes, with three series consisting of $197 million of 6.33% notes due July 15, 2014, $85 million of 6.52% notes due July 15, 2017 and $93 million of 6.67% notes due July 15, 2019. On July 15, 2014, Calamos Investments repaid at maturity $46.2 million of the senior notes outstanding. In December 2008, the Company paid down a portion of its outstanding long-term debt and re-negotiated its debt covenants. As of December 31, 2014 and 2013, the outstanding balances of the notes totaled $46.0 million and $92.1 million, respectively. Of the outstanding balances of the notes, $46.2 million was current as of December 31, 2013.
	The table below summarizes the debt balance at December 31, 2014 and 2013:
	(in thousands)	2014		2013
	Senior unsecured notes:
	6.33% notes due July 15, 2014	$	—	$	46,160
	6.52% notes due July 15, 2017	22,100		22,100
	6.67% notes due July 15, 2019	23,855		23,855
	Total debt	45,955		92,115
	Less current portion of long-term debt	—		(46,160		)
	Total long-term debt	$	45,955	$	45,955
	The table below summarizes the aggregate contractual annual maturities for the total debt balance at December 31, 2014:
	(in thousands)	Contractual
		Maturities
	2015	$	—
	2016	—
	2017	22,100
	2018	—
	2019	23,855
	Thereafter	—
	Total long-term debt	$	45,955
	Under the amended note purchase agreements governing the terms of these notes, Calamos Investments must maintain certain consolidated net worth in addition to leverage, investment and interest coverage ratios. The amended note purchase agreements also contain other covenants that, among other things, restrict the ability of Calamos Investments’ subsidiaries to incur debt and restrict the ability of Calamos Investments or its subsidiaries to create liens and to merge or consolidate, or sell or convey all or substantially all of Calamos Investments’ assets and places certain limitations on distributions and redemptions of equity interests. As of December 31, 2014 and 2013, the Company was in compliance with all covenants.
	The weighted average interest rate on the notes is 6.60% over the remaining life of the notes.

Common_Stock

Common Stock	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Common Stock	Common Stock
	All shares of Class A Common Stock and Class B Common Stock are identical and entitle the holders to the same rights and privileges, including dividend rights and liquidity rights, unless otherwise required by law. However, the holders of Class B Common Stock possess super-voting rights which represents a 97.4% voting interest in the Company.

Profit_Sharing_Plan

Profit Sharing Plan	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Profit Sharing Plan	Profit Sharing Plan
	The Company contributes to a defined contribution profit sharing plan (the "PSP Plan") covering substantially all employees. Contributions to the PSP Plan are at the discretion of the Company and include discretionary profit sharing and matching components. For the years ended December 31, 2014, 2013 and 2012, the Company recorded expense for the contributions to the PSP Plan in the amounts of $3.9 million, $2.5 million and $4.3 million, respectively. This expense is included in employee compensation and benefits on the consolidated statements of operations.

Stock_Based_Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Based Compensation	Stock Based Compensation
	Certain employees of the Company receive stock based compensation comprised of RSUs and stock options under the Company’s incentive compensation plan, which is designed to retain key employees. A total of 10,000,000 shares of CAM’s common stock may be granted under the plan. Historically, RSUs have been settled with newly issued shares so that no cash was used by the Company to settle awards; however, the Company may also use treasury shares upon the exercise of stock options and upon conversion of RSUs.
	RSUs entitle each recipient to receive a share of Class A common stock and a dividend equivalent to the actual dividends declared on CAM’s Class A common stock. RSUs are granted with no strike price and, therefore, the Company receives no proceeds when the RSUs vest. These awards, including accrued dividends, vest at the end of the restriction period, generally not to exceed six years after the grant date, and are expensed on a straight-line basis over this period. For the years ended December 31, 2014, 2013 and 2012, 897,082 RSUs, 838,663 RSUs and 1,484,723 RSUs with an estimated fair value of $10.7 million, $8.9 million and $15.9 million, respectively, were awarded to employees of the Company in accordance with the provisions of the plan. A summary of the RSU activity follows:
		Number of		Weighted
		Shares		Average Grant Date Fair Value
	Outstanding at December 31, 2011	1,818,737		$	14.75
	Granted	1,484,723		10.7
	Forfeited	(359,129	)	13.78
	Exercised upon vesting	(332,225	)	20.11
	Outstanding at December 31, 2012	2,612,106		12.26
	Granted	838,663		10.66
	Forfeited	(407,656	)	12.14
	Exercised upon vesting	(458,138	)	14.96
	Outstanding at December 31, 2013	2,584,975		11.58
	Granted	897,082		11.89
	Forfeited	(501,194	)	11
	Exercised upon vesting	(413,298	)	12.27
	Outstanding at December 31, 2014	2,567,565		11.69
	Converted during the year ended December 31:
	2012	259,258		$	12.34
	2013	310,080		10.87
	2014	294,686		12.23
	As of December 31, 2014, the Company had 2,567,565 RSUs outstanding with a weighted average remaining contractual life of 2.9 years and an aggregate intrinsic value of $34.2 million. The weighted average fair value of RSUs at the date of grant for the years ended December 31, 2014, 2013 and 2012 were $11.89, $10.66 and $10.70 per share, respectively. The aggregate intrinsic value and the fair value of RSUs that vested and were exercised during 2014, 2013 and 2012 was $5.1 million, $5.0 million and $4.1 million, respectively.
	For the years ended December 31, 2014, 2013 and 2012, 413,298 RSUs, 458,138 RSUs and 332,225 RSUs, respectively, were vested and exercised and, after 118,612 RSUs, 148,058 RSUs and 72,967 RSUs, respectively, were withheld for taxes, 294,686 RSUs, 310,080 RSUs and 259,258 RSUs, respectively, were converted, on a one-for-one basis, for shares of CAM’s Class A common stock. The total intrinsic value and the fair value of the converted shares were $3.6 million, $3.4 million and $3.2 million, respectively. The total tax benefit realized in connection with the exercise of the RSUs during 2014, 2013 and 2012 were $471,000, $443,000 and $367,000, respectively, as the Company receives tax benefits equal to the fair value of CAM’s common stock on the exercise date, less the amount attributable to the non-controlling interest.
	Stock options entitle each recipient to purchase a share of Class A common stock in exchange for the stated exercise price upon vesting of each award. Under the plan, the exercise price of each option, which has a 10-year life, equals the market price of the Company’s stock on the date of grant. No awards were granted during the years ended December 31, 2014, 2013 and 2012.
	Summarized information on the Company’s outstanding stock options at December 31, 2014 was as follows:
			Options Outstanding					Options Exercisable
	Range of Exercise Prices		Number of Shares		Average Remaining Contractual Life	Weighted Average Option Price		Number of Shares	Weighted Average Option Price
	$17.80		153,754		1.9	$	17.8	153,754	$	17.8
	$18.00 - $29.11		1,019,588		2.2	$	23.85	1,019,588	$	23.85
	$35.43		255,825		1.1	$	35.43	255,825	$	35.43
			1,429,167		2	$	25.27	1,429,167	$	25.27
	The outstanding options do not have an intrinsic value as the exercise price exceeded the market value.
	A summary of the stock option activity was as follows:
		Number of Shares		Weighted Average Exercise Price
	Outstanding at December 31, 2011	2,345,063		$	23.28
	Forfeited/expired	(149,649	)	22.14
	Outstanding at December 31, 2012	2,195,414		23.36
	Forfeited/expired	(93,846	)	21.94
	Outstanding at December 31, 2013	2,101,568		23.42
	Forfeited/expired	(672,401	)	19.49
	Outstanding at December 31, 2014	1,429,167		25.27
	Exercisable at December 31:
	2012	1,654,100		$	24.14
	2013	1,910,292		23.76
	2014	1,429,167		25.27
	For the years ended December 31, 2014, 2013 and 2012, compensation expense recorded in connection with the RSUs and stock options was $6.6 million, $7.0 million and $5.1 million, respectively, of which $1.5 million, $1.6 million and $1.1 million, respectively, was credited as additional paid-in capital. For the years ended December 31, 2014, 2013 and 2012, the amount of deferred tax asset created was $545,000, $577,000 and $415,000, respectively. As of December 31, 2014, $16.3 million of total unrecognized compensation expense related to unvested stock option and RSU awards is expected to be recognized over a weighted average service period of 2.9 years.

NonOperating_Income

Non-Operating Income	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
Non-Operating Income	Non-Operating Income
	Non-operating income was comprised of the following components for the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013			2012
	Interest income	$	160		$	257		$	385
	Interest expense	(4,669		)	(6,021		)	(6,017		)
	Net interest expense	(4,509		)	(5,764		)	(5,632		)
	Investment income	17,585			29,891			22,073
	Dividend income	1,987			5,355			4,557
	Miscellaneous other income	341			193			207
	Investment and other income	19,913			35,439			26,837
	Non-operating income	$	15,404		$	29,675		$	21,205

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The income tax provision for the years ended December 31, 2014, 2013 and 2012 consists of the following:
	(in thousands)	2014				2013				2012
	Current:
	Federal	$	(1,767	)		$	(216	)		$	2,298
	State:
	CAM portion	(92		)		23				185
	Calamos Interests portion	178				56				(148		)
	Foreign	15				—				—
	Total current income tax provision (benefit)	(1,666		)		(137		)		2,335
	Deferred:
	Federal	6,833				5,867				9,358
	State	620				532				875
	Total deferred income tax provision	7,453				6,399				10,233
	Total income tax provision	$	5,787			$	6,262			$	12,568
	Calamos Investments is subject to certain income-based state taxes; therefore, income tax provision reflects not only the portion attributed to CAM stockholders but also a portion of income tax provision attributable to non-controlling interests.
	The Company files income tax returns in federal, state and foreign tax jurisdictions. The Company is subject to U.S. federal, state and local examinations by tax authorities for years 2011 – 2014. The Internal Revenue Service (“IRS”) completed its examination of the Company’s U.S. income tax returns for years 2011 and 2012 in the third quarter of 2014, resulting in no proposed adjustments.
	The following table reconciles the statutory federal income tax rate to the effective income tax rate for the years ended December 31, 2014, 2013 and 2012, respectively.
		2014			2013			2012
	Statutory U.S. federal income tax rate	35	%		35	%		35	%
	State income taxes, net of federal tax benefits	2	%		2	%		2	%
	Other non-deductible items	0.7	%		0.4	%		0.4	%
	Calamos Investments’ state income taxes	1.1	%		0.3	%		(0.6	)%
	Impact of deferred tax assets valuation allowance	(10.4	)%		(12.2	)%		6.1	%
	Impact of re-measuring certain deferred tax assets	—	%		—	%		(2.3	)%
	Impact of expiring employee stock options	2.4	%		—	%		—	%
	Impact on net deferred tax assets from change in statutory income tax rate	(0.6	)%		(0.3	)%		—	%
	Effective income tax rate	30.2	%		25.2	%		40.6	%
	Calamos Interests state income taxes	(0.9	)%		(0.2	)%		0.5	%
	CAM effective income tax rate	29.3	%		25	%		41.1	%
	Deferred income taxes reflect the expected future tax consequences of temporary differences between carrying amounts and tax bases of the Company’s assets and liabilities. During 2014 and 2013, the Company recorded a $2.0 million and $3.0 million valuation allowance reversal, respectively, based on additional net capital gains realized.
	The significant components of deferred income taxes at December 31, 2014 and 2013 are as follows:
	(in thousands)	2014				2013
	Deferred tax assets:
	Intangible assets	$	34,459			$	42,373
	Capital loss carryforward	169				2,317
	Differences between book basis and tax basis of investments	4,165				3,303
	Stock-based compensation	2,098				2,433
	Other	698				776
	Total deferred tax assets	41,589				51,202
	Valuation allowance on capital loss carryforward	—				(2,148		)
	Total deferred tax assets, net of valuation allowance	41,589				49,054
	Deferred tax liabilities:
	Unrealized net holding gains on investments of available-for-sale securities	902				1,822
	Deferred sales commission	85				137
	Goodwill	81				46
	Other	260				309
	Total deferred tax liabilities	1,328				2,314
	Net deferred tax assets	$	40,261			$	46,740
	Deferred tax assets and liabilities are reflected on the Company’s consolidated statements of financial condition as net deferred tax assets. The current and non-current portions of the net deferred tax asset were $9.2 million and $31.1 million, respectively, at December 31, 2014 and $10.2 million and $36.6 million, respectively, at December 31, 2013.
	As of December 31, 2014, the Company’s net deferred income tax asset attributable to intangible assets was $34.5 million, which is being amortized and creating a tax benefit of $7.9 million per year over 15 years expiring during 2019. This deferred income tax asset was created as a result of the Company purchasing 20,000,000 membership units from CFP in 2004, whereby the Company made an election under Section 754 of the Internal Revenue Code to mark-to-market all qualified assets that it purchased, of which 17,000,000 membership units qualified for the stepped-up basis. Most of the assets receiving the stepped-up basis for tax purposes are in the form of intangible assets, such as management contracts, distribution contracts and intellectual property.
	As of December 31, 2014, the Company’s total capital loss carryforward was $456,000 which will expire in 2017, if not used before the expiration date. As of December 31, 2014, the Company did not have a valuation allowance on this deferred tax asset.
	As a result of Calamos Investments purchasing Black Capital in August 2012, the Company is amortizing goodwill in the amount of $6.4 million over 15 years, creating a deferred income tax liability.
	As of December 31, 2014 and 2013, the Company had no material unrecognized tax benefits and it does not anticipate any unrecognized tax benefits arising in the next 12 months that would result in a material change to its financial position. A reconciliation is not provided, as the beginning and ending amounts of unrecognized benefits are zero with no interim additions, reductions or settlements.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	The following table reflects the calculation of basic and diluted earnings per share:
	(in thousands, except per share amounts)	2014			2013			2012
	Earnings per share – basic:
	Earnings available to common shareholders	$	13,530		$	18,628		$	18,192
	Weighted average shares outstanding	18,275			19,904			20,334
	Earnings per share – basic	$	0.74		$	0.94		$	0.89
	Earnings per share – diluted:
	Earnings available to common shareholders	$	13,530		$	18,628		$	18,192
	Weighted average shares outstanding	18,275			19,904			20,334
	Dilutive impact of restricted stock units	714			448			412
	Weighted average shares outstanding	18,989			20,352			20,746
	Earnings per share – diluted	$	0.71		$	0.92		$	0.88
	When dilutive, diluted shares outstanding for 2014, 2013 and 2012 are calculated (a) assuming that Calamos Interests exchanged all of their ownership interest in Calamos Investments and their CAM Class B common stock for shares of CAM’s Class A common stock (the "Exchange") and (b) including the effect of outstanding dilutive equity incentive compensation awards. As of December 31, 2014, 2013 and 2012, the impact of the Exchange was anti-dilutive and, therefore, excluded from the calculation of diluted earnings per share.
	The Company uses the treasury stock method to reflect the dilutive effect of unvested RSUs and unexercised stock options on diluted earnings per share. Under the treasury stock method, if the average market price of common stock increases above the option’s exercise price, the proceeds that would be assumed to be realized from the exercise of the option would be used to acquire outstanding shares of common stock. However, the awards may be anti-dilutive even when the market price of the underlying stock exceeds the option’s exercise price. This result is possible because compensation cost attributed to future services and not yet recognized is included as a component of the assumed proceeds upon exercise. The dilutive effect of such options and RSUs would increase the weighted average number of shares used in the calculation of diluted earnings per share.
	The Company amended its certificate of incorporation requiring that the Exchange be based on a fair value approach (details of the amendment are set forth in the Company’s Schedule 14C filed with the Securities and Exchange Commission on January 12, 2009). The amendment results in the same or fewer shares of Class A common stock being issuable at the time of the Exchange.
	The shares issuable upon the Exchange as presented are estimated solely on the formula as described in Schedule 14C that does not necessarily reflect all inputs used in a fair valuation. It is critical to note that this formula does not incorporate certain economic factors and as such, in the event of an actual Exchange, the majority of the Company’s independent directors may determine the fair market value of CAM’s net assets and its ownership in Calamos Investments. For example, premiums and/or discounts for control and marketability as well as a different discount rate for future cash flows may be applied. Therefore, the directors’ valuation may result in the actual number of shares being materially different from the shares presented. Further, based upon currently available information, the Company believes it is unlikely that any Exchange would transpire without a fair market valuation of CAM’s net assets and possibly an agreement by Calamos Interests to Exchange, based upon that fair market valuation.
	The following table shows the number of shares which were excluded from the computation of diluted earnings per share as they were anti-dilutive:
		2014		2013			2012
	Shares of Class A common stock issuable upon an Exchange of Calamos Interests’ ownership in Calamos Investments*	27,916,544		34,594,896			36,735,145
	Restricted stock units	174,523		558,473			—
	Stock options	1,429,167		2,101,568			2,195,414
	Total	29,520,234		37,254,937			38,930,559
	* Number of shares calculated with the value of Calamos Investments determined by using the closing price of our shares as of December 31, 2014 ($13.32), December 31, 2013 ($11.84) and December 31, 2012 ($10.57) as well as assuming said closing prices fully reflect all of CAM's assets; including the application of a 12% discount rate to certain deferred tax assets at each of December 31, 2014, 2013 and 2012. The value of Calamos Investments is then multiplied by Calamos Interests' percentage ownership in Calamos Investments, with the result divided by the applicable year-end closing price. See Note 2, Summary of Significant Accounting Policies - Principles of Consolidation, for a description of certain assets owned by CAM.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	In the normal course of business, the Company enters into agreements that include indemnities in favor of third parties, such as engagement letters with advisors and consultants, distribution agreements and service agreements. In accordance with the Company’s by-laws, the Company has also agreed to indemnify its directors, officers, employees and agents in certain cases. Certain agreements do not contain any limits on the Company’s liability and, therefore, it is not possible to estimate the Company’s potential liability under these indemnities. In certain cases, the Company may have recourse against third parties with respect to these indemnities. Further, the Company maintains insurance policies that may provide coverage against certain claims under these indemnities.
	In the normal course of business, the Company may be party to various legal proceedings from time to time. Management believes that a current complaint filed against CAL and CFS, alleging breaches of fiduciary duties with respect to the receipt of advisory, distribution and servicing fees paid by an open-end investment company advised by CAL, is without merit and CAL and CFS intend to defend themselves vigorously against the allegations. Currently, management believes that the ultimate resolution of this complaint will not materially affect the Company’s business, financial position or results of operations and that the likelihood of a material adverse impact is remote.
	The Company leases office space and computer equipment under long-term operating leases expiring at various dates through fiscal year 2025. For the years ended December 31, 2014, 2013 and 2012 lease expenses were $5.6 million, $5.6 million and $5.2 million, respectively. As of December 31, 2014, the Company’s aggregate future minimum payments for operating leases having initial or non-cancelable terms greater than one year are payable as follows:
		Minimum
	(in thousands)	Payments
	Year ended December 31:
	2015	$	5,433
	2016	4,705
	2017	4,840
	2018	4,953
	2019	5,030
	Thereafter	27,906
	Total minimum lease payments	$	52,867

Regulatory_and_Net_Capital_Req

Regulatory and Net Capital Requirements	12 Months Ended
	Dec. 31, 2014
Regulatory Capital Requirements [Abstract]
Regulatory and Net Capital Requirements	Regulatory and Net Capital Requirements
	As a broker-dealer, CFS is subject to the Securities and Exchange Commission’s Uniform Net Capital Rule (Rule 15c3-1), which requires the maintenance of minimum net capital, as defined, and requires that the ratio of aggregate indebtedness to net capital (net capital ratio), as defined, shall not exceed 15 to 1. As of December 31, 2014 and 2013, the net capital, the excess of the required net capital and the net capital ratio were as follows:
	(in thousands)	2014		2013
	Net capital	$	1,791	$	6,230
	Excess of required net capital	$	1,003	$	5,394
	Net capital ratio	6.60 : 1.0		2.01 : 1.0

Concentration_Risk

Concentration Risk	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Concentration Risk	Concentration Risk
	For the years ended December 31, 2014, 2013 and 2012, the percentage of revenues derived from services provided to three Company-sponsored open-end funds, the Calamos Growth Fund, the Calamos Growth and Income Fund and the Calamos Market Neutral Fund were as follows:
		2014		2013		2012
	Calamos Growth Fund	18	%	21	%	26	%
	Calamos Growth and Income Fund	14	%	15	%	15	%
	Calamos Market Neutral Fund	14	%	10	%	7	%

Quarterly_Financial_Informatio

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited)
		As of or for the Quarter Ended
		2014								2013
		Dec. 31		Sept. 30		30-Jun		31-Mar		Dec. 31		Sept. 30		30-Jun		31-Mar
	(in millions)
	Assets under management*	$	23,506	$	24,514	$	25,755	$	26,147	$	26,543	$	26,618	$	25,797	$	28,324
	(in thousands, except share data)
	Total revenue	$	60,495	$	63,532	$	63,005	$	63,930	$	66,522	$	64,965	$	66,690	$	70,953
	Total operating expenses	45,868		47,679		46,371		49,854		44,579		49,541		48,286		48,838
	Operating income	$	14,627	$	15,853	$	16,634	$	14,076	$	21,943	$	15,424	$	18,404	$	22,115
	Net income attributable to CAM	$	4,794	$	3,369	$	3,228	$	2,139	$	10,856	$	2,697	$	1,841	$	3,234
	Diluted earnings per share	$	0.25	$	0.18	$	0.17	$	0.11	$	0.54	$	0.13	$	0.09	$	0.16
	Diluted shares outstanding	18,808,798		18,781,856		19,048,456		19,805,828		20,214,360		20,387,651		20,661,447		20,836,996
	*Assets under management do not include assets for which the Company provides model portfolio design and oversight.

Recently_Issued_Accounting_Pro

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2014
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements
	We have reviewed all newly issued accounting pronouncements that are applicable to our business and to the preparation of our consolidated financial statements, including those not yet required to be adopted. We do not believe any such pronouncements will have a material effect on the Company’s financial position or results of operations. Accounting guidance that will become effective in future years, with respect to the Company’s consolidated financial statements, is described below:
	In February 2015, the Financial Accounting Standards Board ("FASB") issued an accounting update amending the consolidation requirements under GAAP. This standard modifies existing consolidation guidance for reporting organizations that are required to evaluate whether they should consolidate certain legal entities. This guidance is effective for annual and interim periods beginning after December 15, 2015, and requires either a retrospective or a modified retrospective approach to adoption. Early adoption is permitted. The Company is currently evaluating the potential impact of this standard on its results of operations, cash flows or financial position, as well as the available transition methods.
	In May 2014, the FASB issued new guidance on revenue from contracts with customers. The new revenue recognition standard provides a five-step analysis of transactions to determine when and how revenue is recognized. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance is effective for annual and interim periods beginning after December 15, 2016 and shall be applied retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. Early application of this standard is not permitted. The Company's effective date is January 1, 2017. The Company is evaluating the effect of adopting this new accounting guidance but does not expect adoption will have a material impact on its results of operations, cash flows or financial position.

Subsequent_Event_Notes

Subsequent Event (Notes)	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event
	On January 13, 2015, Calamos Investments made a $10.0 million distribution, of which $7.8 million or 77.8% was distributed to Calamos Interests.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation
	The consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”), which require the use of estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Management believes the accounting estimates are appropriate and reasonably stated; however, due to the inherent uncertainties in making estimates, actual amounts could differ from these estimates.
Principles of Consolidation	Non-controlling interest in Calamos Investments is derived by multiplying the historical equity of Calamos Investments by the Calamos Interests’ aggregate ownership percentage for the periods presented. Issuances and repurchases of CAM’s common stock may result in changes to CAM’s ownership percentage and to the non-controlling interests’ ownership percentage of Calamos Investments with resulting changes reflected in the consolidated statements of changes in equity. Income is allocated based on the average ownership interest during the period in which the income is earned.
	CAM owns certain assets to which common stockholders have exclusive economic rights.
	These portions of CAM’s income and expense are not affected by non-controlling interests.
	Calamos Investments, through a wholly owned subsidiary, is indirectly the general partner and controls the operations of Calamos Arista Strategic Fund LP (formerly Black Strategic Fund, LP), a U.S. feeder fund and Calamos Arista Strategic Fund Ltd, an offshore feeder fund both to Calamos Arista Strategic Master Fund LTD (formerly Black Strategic Master Fund Ltd.), a hedge fund in the Cayman Islands. As Calamos Investments is the general partner and controls the operations of Calamos Arista Strategic Fund LP and Calamos Arista Strategic Fund Ltd, the results of these partnerships and the master fund are included in the Company’s consolidated financial results. Calamos Arista Strategic Fund LP was liquidated on December 26, 2014. The partnership redemptions were completed subsequent to December 31, 2014, therefore, the amount due to non-controlling interest of $7.7 million related to this partnership investment is presented in liabilities of partnership investments in our consolidated statements of financial condition for the year ended December 31, 2014. Calamos Investments, through its wholly owned subsidiaries and affiliates, is indirectly the general partner and controls the operations of Calamos Global Opportunities Fund LP, for which it acquired a majority interest in the partnership during the second quarter of 2014. The results of this partnership are included in the Company's consolidated financial statements for the year ended December 31, 2014. The operations of Calamos International Growth Fund LP were controlled by CAL, the general partner. In December 2013, the limited partners of Calamos International Growth Fund LP redeemed all of their interests in the fund. As a result, the Company deconsolidated Calamos International Growth Fund LP and accounted for this partnership investment using the equity method as of December 31, 2013. Calamos International Growth Fund LP was dissolved on April 10, 2014. See Note 7, Partnership Investments, for more discussion regarding these funds.
	For the periods the partnerships are consolidated, the assets and liabilities of the partnerships are presented as partnership investments and liabilities of partnership investments, respectively, in the consolidated statements of financial condition. The net income for these partnerships are included in investment and other income in the consolidated statements of operations, and the change in partnership investments is included in contributions to or distributions from partnership investments in the consolidated statements of cash flows. The underlying assets and liabilities that are being consolidated are described in Note 7, Partnership Investments. The combined interests of all of the consolidated partnerships not owned by the Company and that are redeemable at the option of the holder, are presented as redeemable non-controlling interest in partnership investments in the Company’s consolidated financial statements for the periods those partnerships were consolidated.
	The Company holds non-controlling interests in certain other partnership investments that are included in partnership investments in the consolidated statements of financial condition. These other partnership investments are accounted for under the equity method.
	Principles of Consolidation
	The Company consolidates investments in which the Company’s ownership exceeds 50% or in which the Company operates and controls the business and affairs of the entity or is deemed to be the primary beneficiary. In order to make this determination, an analysis is performed to determine if the investment in an affiliate or partnership is a variable interest entity ("VIE"). The Company has evaluated its investments in affiliates and partnerships and has concluded that they are not VIEs. With respect to partnership investments, the limited partners have no control of the business and affairs of the partnership, no substantive ability to dissolve (liquidate) the partnership, or otherwise remove the general partner (CAL and Calamos Investments) without cause or have other substantive rights.
	The consolidated financial statements include the financial statements of CAM, Calamos Investments, Calamos Investments’ wholly- and majority-owned subsidiaries, and the Company’s partnerships in which it owns a majority interest or in which it has operating control. The equity method of accounting is used for investments in which the Company has significant influence, but less than 50% ownership. All significant intercompany balances and transactions have been eliminated.
Reclassifications	Reclassifications
	The Company changed the presentation of assets and liabilities of partnership investments from a net basis to a gross basis in the consolidated statements of financial condition. Amounts previously reported have been reclassified to conform to the current period's presentation.
Cash and Cash Equivalents	Cash and Cash Equivalents
	All highly liquid financial instruments with maturities of three months or less from date of purchase, consisting primarily of investments in insured money market accounts and money market funds, are considered cash equivalents
Receivables from Customers	Receivables from Customers
	Receivables from customers represent balances arising from contractual investment advisory services provided to separate account customers and are recorded on an accrual basis. Provisions for bad debt expense during the years ended December 31, 2014, 2013, and 2012 and allowance for doubtful accounts as of December 31, 2014 and 2013, were not material
Investment Securities	Investment Securities
	The Company carries its investment securities at fair value. For a majority of the Company’s investments, fair values are determined based upon quoted prices in active markets. If quoted market prices are not available, the Company uses matrix, model or other similar pricing methods to determine fair value. Investment securities transactions are recorded on a trade-date basis.
	Investment securities are classified as available-for-sale as the Company does not intend to trade these securities in the near term. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported, net of income tax, as a separate component of equity until realized. Realized gains and losses from the sale of available-for-sale securities are determined on a specific identification basis and are included in investment and other income in the consolidated statements of operations.
	Investment securities that are classified as trading securities are carried at fair value with all changes in the value of the securities going through current earnings. Therefore, both realized and unrealized gains and losses on these securities are included in investment and other income in the consolidated statements of operations.
	On a quarterly basis, the Company conducts reviews to assess whether an other-than-temporary impairment exists on its available-for-sale investment securities. Other-than-temporary declines in value may exist when the fair value of an investment security has been below the carrying value for an extended period of time. If an other-than-temporary decline in value is determined to exist, the unrealized investment loss, net of tax is recognized in the consolidated statements of operations in the period in which the other-than-temporary decline in value occurs, as well as an accompanying permanent adjustment to accumulated other comprehensive income.
Derivative Assets and Liabilities	Derivative Assets and Liabilities
	From time to time, the Company enters into derivative contracts to mitigate the negative impact that changes in security prices may have on the investment portfolio. The Company does not measure effectiveness or meet the criteria for hedge accounting and, therefore, records the changes in the fair value of these instruments in investment and other income in the consolidated statements of operations. The Company classifies derivatives as derivative assets and derivative liabilities in the consolidated statements of financial condition.
Goodwill	Goodwill
	The Company’s goodwill represents the future economic benefits arising from Calamos Investments’ acquisition of Black Capital, LLC (“Black Capital”) that are not individually identified and separately recognized. Goodwill is assessed for impairment at the reporting unit level, Calamos Investments, at least annually, or whenever events or circumstances occur indicating that an impairment may have occurred. The goodwill impairment test is a two-step process. The first step requires the Company to estimate the fair value of its reporting unit and compare the fair value to the reporting unit’s carrying amount. If the fair value exceeds the carrying amount, the goodwill is not considered impaired. To the extent the reporting unit’s carrying amount exceeds its fair value, the reporting unit’s goodwill may be impaired and the second step of the impairment test must be performed. The second step involves assigning the reporting unit’s fair value to all of its recognized and unrecognized assets and liabilities as if the reporting unit had been acquired in a business combination in order to determine the implied fair value of the reporting unit’s goodwill. The implied fair value of the reporting unit’s goodwill is then compared to the carrying amount of goodwill to quantify an impairment loss, if any, which would equal the excess of the carrying amount of goodwill over the goodwill’s implied fair value.
Property and Equipment	Property and Equipment
	Property and equipment are recorded at cost less accumulated depreciation and amortization. Depreciation and amortization is provided on a straight-line basis over the estimated useful lives of the assets, ranging from three to twenty years. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining term of the lease, ranging from five to twenty years.
	Property and equipment are reviewed for impairment when there is an indication that the carrying amount of an asset may not be recoverable. Carrying values are not recoverable when the undiscounted cash flows estimated to be generated by the assets are less than their carrying value. When an asset is determined to not be recoverable, the impairment loss is measured based on the excess, if any, of the carrying value of the asset over its respective fair value. Fair value is determined by discounted cash flows models, appraisals or other applicable methods.
Internally Developed Software	Internally Developed Software
	Certain internal and external development costs incurred in connection with developing or obtaining software for internal use are capitalized. These capitalized costs are included in property and equipment, net in the consolidated statements of financial condition and are amortized using the straight-line method over their estimated useful lives, ranging from three to five years. On an annual basis, the Company conducts reviews to assess the functionality and remaining useful lives of the capitalized software. Impairments of these assets, if any, are recognized in the consolidated statements of operations in the period in which the impairment occurs.
Restricted Cash	Restricted Cash
	The Company has a $429,000 security deposit that is restricted from the Company’s general corporate use and is being reported in other non-current assets in the consolidated statements of financial condition.
Compensation Plans	Compensation Plans
	The Company has an incentive stock plan that provides for certain employees of the Company to receive stock based compensation in the form of restricted stock units (“RSUs”) and stock options. RSUs are convertible on a one-for-one basis into shares of the Company’s common stock. Stock option awards are based on shares of the Company’s common stock. The Company estimates the fair value of the options as of the grant date using the Black-Scholes option-pricing model. Stock based compensation expense is recognized based on the grant-date fair value of the award. The Company records compensation expense on a straight-line basis over the service period.
Revenue Recognition	Revenue Recognition
	The Company earns investment management fees by providing services pursuant to the terms of the underlying advisory contract. Fees are based on a contractual investment advisory fee applied to the assets in each portfolio. Any fees collected in advance are deferred and recognized over the period earned. Performance-based advisory fees from certain separate accounts are recognized annually upon completion of the contract year and based upon either (1) the difference between the investment returns on a client’s portfolio compared to a benchmark index or (2) the absolute percentage of gain in the client’s account. Performance-based advisory fees from the open-end funds are recognized monthly when earned and are based upon the differences between the investment returns of the respective fund compared to a benchmark index.
	Distribution and underwriting fees consist primarily of Rule 12b-1 distribution and/or service fees from the open-end funds, contingent deferred sales charges on the redemption of open-end fund shares and sales charges earned on open-end funds. Distribution service fees are accrued monthly as services are performed and are based on the average daily assets of the open-end funds. Contingent deferred sales charges are recorded on a trade-date basis when earned, and sales charges are recorded on the settlement date.
Net Interest Expense	Net Interest Expense
	Net interest expense represents interest expense incurred on debt net of interest income generated from cash and cash equivalents. Interest income is recognized when earned, and interest expense is recorded when incurred.
Investment and Other Income	Investment and Other Income
	Investment and other income is primarily comprised of: realized gains (losses) from all investment securities and partnership investments; unrealized gains (losses) on trading securities and partnership investments; realized and unrealized gains (losses) on derivatives; gains (losses) on foreign currency translation; and dividend income. Dividend income is recognized on the ex-dividend date.
Foreign Currency	Foreign Currency
	Foreign currency balances are revalued into U.S. dollars, which is the functional currency of the Company, at prevailing exchange rates on the reporting date. Revenues earned and expenses incurred in foreign currency are revalued at average exchange rates during the reporting period. Gains and losses arising from the revaluation of account balances denominated in foreign currencies are recognized in investment and other income in the consolidated statements of operations.
Income Taxes	Income Taxes
	Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the temporary differences between the financial statement carrying amount of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. During 2014 and 2013, the Company recorded valuation allowance adjustments to reduce its deferred income tax assets to an amount that is more likely than not to be realized based on available evidence at the time estimates are made.
	Determining a valuation allowance requires management to make significant judgments and assumptions. In determining a valuation allowance the Company uses historical and forecasted future realized and unrealized gains and losses on its investment, ongoing tax planning strategies, and forecasts of future taxable income. Each quarter the Company re-evaluates its estimates related to its valuation allowance, including its assumptions about future taxable income. The Company’s capital loss carryforward is used against realized gains on its investment, derivative assets, derivative liabilities and partnership investments, using its tax harvesting strategies. See Note 16, Income Taxes for more discussion related to the deferred tax valuation allowance.
	Future interest or penalties related to uncertain income tax positions are recognized in income tax provision when determined. The Company did not record any accrued interest or penalties related to uncertain tax positions through December 31, 2014.
Advertising Costs	Advertising Costs
	Advertising costs are expensed as incurred and are included in marketing and sales promotion expenses in the consolidated statements of operations.
Earnings Per Share	Earnings Per Share
	Basic earnings per share is computed by dividing net income attributable to CAM by the weighted average number of shares of Class A and Class B common stock outstanding during each year. Shares issued or repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted earnings per share reflects the potential dilution that would occur if RSUs and stock options granted to participants of the Company incentive compensation plan were exercised and if the Calamos Interests exchanged all of their ownership interest in Calamos Investments and their Class B common stock for shares of Class A common stock. Diluted shares which result in anti-dilution are excluded from the diluted earnings per share calculation and are detailed in Note 17, Earnings Per Share.

RelatedParty_Transactions_Tabl

Related-Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Summary of total fees earned from affiliates	The table below summarizes the total fees earned from affiliates identified above during the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013		2012
	Investment management fees from:
	Open-end funds	$	119,898		$	124,875	$	158,040
	Closed-end funds	57,911			53,981		49,842
	Totals	$	177,809		$	178,856	$	207,882
	Distribution fees from open-end funds	$	48,942		$	53,143	$	66,604
	Portfolio accounting fees from:
	Open-end funds	$	1,756		$	1,810	$	2,239
	Closed-end funds	727			679		623
	Totals	$	2,483		$	2,489	$	2,862
Fees that have been recorded as expense allocations	The following table summarizes fees that have been recorded as expense allocations during the twelve months ended and the net receivable balance as of December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013		2012
	Expense allocated from the Company to CPH	$	590		$	556	$	606
	Expense allocated from the Company to CFP	243			236		245
	Expense allocated from the Company to Dragon	16			16		18
	Total expenses allocated from the Company to affiliates	849			808		869
	Expense allocated from CPH and CFP to the Company	173			151		196
	Net expense allocated from the Company to affiliates	$	676		$	657	$	673
	Net receivable for management services from CPH	$	40		$	43	$	1
	Net receivable (payable) for management services from CFP	$	(11	)	$	9	$	4
	Net receivable for management services from Dragon	$	1		$	1	$	41
	Other receivables as a result of Black Capital purchase	$	—		$	—	$	38

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Summary of investment securities	The following table provides a summary of investment securities as of December 31, 2014 and 2013:
	(in thousands)
	December 31, 2014		Cost			Unrealized Gains			Unrealized Losses				Fair Value
	Available-for-sale securities:
	Funds
	Equity
	Global Growth		$	142,610		$	5,275		$	(1,872	)		$	146,013
	U.S. Growth		64,526			3,194			(410		)		67,310
	Value		9,979			286			(171		)		10,094
	Alternative		40,752			1,283			(4		)		42,031
	Fixed Income/High Yield		17,596			1			(423		)		17,174
	Convertible		10,163			15			(1		)		10,177
	Multi-Strategy		1,494			198			(9		)		1,683
	Total Funds		287,120			10,252			(2,890		)		294,482
	Common stock		136			125			—				261
	Total available-for-sale securities		$	287,256		$	10,377		$	(2,890	)		$	294,743
	Trading securities:
	Funds
	Equity
	U.S. Growth		$	52,147		$	33		$	(6,964	)		$	45,216
	Total investment securities												$	339,959
	(in thousands)
	December 31, 2013		Cost			Unrealized Gains			Unrealized Losses				Fair Value
	Available-for-sale securities:
	Funds
	Equity
	Global Growth		$	214,811		$	11,097		$	(15	)		$	225,893
	U.S. Growth		55,109			2,971			(436		)		57,644
	Value		9,886			315			(243		)		9,958
	Alternative		35,436			2,000			—				37,436
	Fixed Income/High Yield		98,834			429			(4		)		99,259
	Convertible		142			3			—				145
	Multi-Strategy		1,272			130			(2		)		1,400
	Total Funds		415,490			16,945			(700		)		431,735
	Common stock		133			80			—				213
	Total available-for-sale securities		$	415,623		$	17,025		$	(700	)		$	431,948
	Trading securities:
	Funds
	Equity
	U.S. Growth		$	48,539		$	320		$	(8,566	)		$	40,293
	Total investment securities												$	472,241
Changes in investment securities	The following table provides a summary of changes in investment securities for the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013			2012
	Available-for-sale securities:
	Proceeds from sales	$	293,662		$	524,968		$	344,911
	Gross realized gains on sales	$	11,024		$	25,882		$	28,587
	Trading securities:
	Unrealized gains (losses)	$	1,315		$	(8,813	)	$	94
Summary of tax (provision) benefit on unrealized gains	The table below summarizes the tax provision (benefit) on unrealized gains and gains reclassified out of accumulated other comprehensive income (loss) on available-for-sale securities for the years ended December 31, 2014, 2013 and 2012:
		2014										2013									2012
	(in thousands)	Before-Tax Amount			Tax Provision (Benefit)			After-Tax				Before-Tax Amount			Tax Provision (Benefit)			After-Tax			Before-Tax Amount			Tax Provision (Benefit)			After-Tax
								Amount										Amount									Amount
	Available-for-sale securities:
	Changes in unrealized gains	$	3,173		$	404		$	2,769			$	39,630		$	3,793		$	35,837		$	19,027		$	1,554		$	17,473
	Reclassification adjustment for realized gains included in income	(12,012		)	(1,324		)	(10,688		)		(19,732		)	(1,679		)	(18,053		)	(20,512		)	(1,676		)	(18,836		)
	Other comprehensive income (loss)	$	(8,839	)	$	(920	)	$	(7,919	)		$	19,898		$	2,114		$	17,784		$	(1,485	)	$	(122	)	$	(1,363	)

Partnership_Investments_Tables

Partnership Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Partnership Investments [Abstract]
Partnership Investments	Presented below are the underlying assets and liabilities of the partnerships that the Company reports on a consolidated basis, as well as partnership investments that the Company accounts for under the equity method. These investments are presented as partnership investments and liabilities of partnership investments, respectively, in its consolidated statements of financial condition as of December 31, 2014 and 2013.
	(in thousands)	2014			2013
	Consolidated partnerships:
	Assets
	Securities owned	$	103,079		$	29,149
	Cash and cash equivalents	39,205			12,208
	Receivables for securities sold	—			1,076
	Other current assets	1,188			30
	Exchange-traded option contracts	201			150
	Total assets of consolidated partnerships	$	143,673		$	42,613
	Liabilities
	Securities sold not yet purchased	$	—		$	(10,670	)
	Payables for securities purchased	(2,256		)	(1,576		)
	Due to non-controlling interest in partnership investments	(7,719		)	—
	Accrued expenses and other current liabilities	(142		)	(76		)
	Exchange-traded options contracts	—			(56		)
	Total liabilities of consolidated partnerships	$	(10,117	)	$	(12,378	)
	Equity method investment in partnerships	$	50		$	3,812

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair value of assets and liabilities measured on recurring basis	The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2014 and 2013. Foreign currency contracts are carried in the Company's partnership investments and are presented on a net basis where the right of offset exists, and had no impact for either period presented.
					Fair Value Measurements Using
	(in thousands)	December 31, 2014			Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)			Significant Other Observable Inputs (Level 2)
	Description
	Cash and cash equivalents
	Money market funds	$	1,209		$	1,209		$	—
	Investment securities (Note 5)
	Funds
	Equity
	Global Growth	146,013			146,013			—
	U.S. Growth	112,526			112,526			—
	Value	12,218			12,218			—
	Alternative	42,031			42,031			—
	Fixed Income/High Yield	17,174			12,174			5,000
	Convertible	11,021			11,021			—
	Multi-Strategy	1,683			1,683			—
	Total Funds	342,666			337,666			5,000
	Common stock	261			261			—
	Investment securities	342,927			337,927			5,000
	Securities and derivatives owned by partnership investments (Note 7)
	Common stocks	51,403			26,237			25,166
	Preferred stocks	5,736			2,281			3,455
	Convertible bonds	41,119			—			41,119
	Corporate bonds	4,821			—			4,821
	Foreign currency	513			513			—
	Money market funds	37,060			7,851			29,209
	Exchange-traded put option contracts	201			201			—
		140,853			37,083			103,770
	Securities sold but not yet purchased (Note 5)
	Common stocks	(2,968		)	(2,968		)	—
	Total	$	482,021		$	373,251		$	108,770
					Fair Value Measurements Using
	(in thousands)	December 31, 2013			Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs
					and Liabilities			(Level 2)
	Description				(Level 1)
	Cash and cash equivalents
	Money market funds	$	1,752		$	1,752		—
	Investment securities (Note 5)
	Funds
	Equity
	Global Growth	225,892			225,892			—
	U.S. Growth	97,936			97,936			—
	Value	9,959			9,959			—
	Alternative	37,436			37,436			—
	Fixed Income/High Yield	99,260			99,260			—
	Convertible	145			145			—
	Multi-Strategy	1,400			1,400			—
	Total Funds	472,028			472,028			—
	Common stock	213			213			—
	Investment securities	472,241			472,241			—
	Securities and derivatives owned by partnership investments (Note 7)
	Common stocks	29,149			29,149			—
	Exchange-traded put option contracts	150			150			—
		29,299			29,299			—
	Securities sold but not yet purchased by partnership investments (Note 7)
	Common stocks	(10,185		)	(10,185		)	—
	Exchange-traded funds	(485		)	(485		)	—
	Exchange-traded call option contracts	(56		)	(56		)	—
		(10,726		)	(10,726		)	—
	Total	$	492,566		$	492,566		$	—

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and equipment and related accumulated depreciation	As of December 31, 2014 and 2013, property and equipment and related accumulated depreciation were as follows:
	(in thousands)	2014			2013
	Property and equipment:
	Furniture, fixtures and equipment	$	25,421		$	27,617
	Leasehold improvements	32,062			32,062
	Computer software	17,908			17,650
	Total costs	75,391			77,329
	Accumulated depreciation and amortization	(61,145		)	(60,339		)
	Property and equipment, net	$	14,246		$	16,990

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of long-term debt	The table below summarizes the debt balance at December 31, 2014 and 2013:
	(in thousands)	2014		2013
	Senior unsecured notes:
	6.33% notes due July 15, 2014	$	—	$	46,160
	6.52% notes due July 15, 2017	22,100		22,100
	6.67% notes due July 15, 2019	23,855		23,855
	Total debt	45,955		92,115
	Less current portion of long-term debt	—		(46,160		)
	Total long-term debt	$	45,955	$	45,955
Aggregate contractual annual maturities for long-term debt	The table below summarizes the aggregate contractual annual maturities for the total debt balance at December 31, 2014:
	(in thousands)	Contractual
		Maturities
	2015	$	—
	2016	—
	2017	22,100
	2018	—
	2019	23,855
	Thereafter	—
	Total long-term debt	$	45,955

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of the RSU activity	A summary of the RSU activity follows:
		Number of		Weighted
		Shares		Average Grant Date Fair Value
	Outstanding at December 31, 2011	1,818,737		$	14.75
	Granted	1,484,723		10.7
	Forfeited	(359,129	)	13.78
	Exercised upon vesting	(332,225	)	20.11
	Outstanding at December 31, 2012	2,612,106		12.26
	Granted	838,663		10.66
	Forfeited	(407,656	)	12.14
	Exercised upon vesting	(458,138	)	14.96
	Outstanding at December 31, 2013	2,584,975		11.58
	Granted	897,082		11.89
	Forfeited	(501,194	)	11
	Exercised upon vesting	(413,298	)	12.27
	Outstanding at December 31, 2014	2,567,565		11.69
	Converted during the year ended December 31:
	2012	259,258		$	12.34
	2013	310,080		10.87
	2014	294,686		12.23
Information on the Company's outstanding stock options	Summarized information on the Company’s outstanding stock options at December 31, 2014 was as follows:
			Options Outstanding					Options Exercisable
	Range of Exercise Prices		Number of Shares		Average Remaining Contractual Life	Weighted Average Option Price		Number of Shares	Weighted Average Option Price
	$17.80		153,754		1.9	$	17.8	153,754	$	17.8
	$18.00 - $29.11		1,019,588		2.2	$	23.85	1,019,588	$	23.85
	$35.43		255,825		1.1	$	35.43	255,825	$	35.43
			1,429,167		2	$	25.27	1,429,167	$	25.27
Summary of the stock option activity	A summary of the stock option activity was as follows:
		Number of Shares		Weighted Average Exercise Price
	Outstanding at December 31, 2011	2,345,063		$	23.28
	Forfeited/expired	(149,649	)	22.14
	Outstanding at December 31, 2012	2,195,414		23.36
	Forfeited/expired	(93,846	)	21.94
	Outstanding at December 31, 2013	2,101,568		23.42
	Forfeited/expired	(672,401	)	19.49
	Outstanding at December 31, 2014	1,429,167		25.27
	Exercisable at December 31:
	2012	1,654,100		$	24.14
	2013	1,910,292		23.76
	2014	1,429,167		25.27

NonOperating_Income_Tables

Non-Operating Income (Tables)	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
Non-operating income	Non-operating income was comprised of the following components for the years ended December 31, 2014, 2013 and 2012:
	(in thousands)	2014			2013			2012
	Interest income	$	160		$	257		$	385
	Interest expense	(4,669		)	(6,021		)	(6,017		)
	Net interest expense	(4,509		)	(5,764		)	(5,632		)
	Investment income	17,585			29,891			22,073
	Dividend income	1,987			5,355			4,557
	Miscellaneous other income	341			193			207
	Investment and other income	19,913			35,439			26,837
	Non-operating income	$	15,404		$	29,675		$	21,205

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax provision	The income tax provision for the years ended December 31, 2014, 2013 and 2012 consists of the following:
	(in thousands)	2014				2013				2012
	Current:
	Federal	$	(1,767	)		$	(216	)		$	2,298
	State:
	CAM portion	(92		)		23				185
	Calamos Interests portion	178				56				(148		)
	Foreign	15				—				—
	Total current income tax provision (benefit)	(1,666		)		(137		)		2,335
	Deferred:
	Federal	6,833				5,867				9,358
	State	620				532				875
	Total deferred income tax provision	7,453				6,399				10,233
	Total income tax provision	$	5,787			$	6,262			$	12,568
Reconciliation of the statutory federal income tax rate to the effective income tax rate	The following table reconciles the statutory federal income tax rate to the effective income tax rate for the years ended December 31, 2014, 2013 and 2012, respectively.
		2014			2013			2012
	Statutory U.S. federal income tax rate	35	%		35	%		35	%
	State income taxes, net of federal tax benefits	2	%		2	%		2	%
	Other non-deductible items	0.7	%		0.4	%		0.4	%
	Calamos Investments’ state income taxes	1.1	%		0.3	%		(0.6	)%
	Impact of deferred tax assets valuation allowance	(10.4	)%		(12.2	)%		6.1	%
	Impact of re-measuring certain deferred tax assets	—	%		—	%		(2.3	)%
	Impact of expiring employee stock options	2.4	%		—	%		—	%
	Impact on net deferred tax assets from change in statutory income tax rate	(0.6	)%		(0.3	)%		—	%
	Effective income tax rate	30.2	%		25.2	%		40.6	%
	Calamos Interests state income taxes	(0.9	)%		(0.2	)%		0.5	%
	CAM effective income tax rate	29.3	%		25	%		41.1	%
Significant components of deferred income taxes	The significant components of deferred income taxes at December 31, 2014 and 2013 are as follows:
	(in thousands)	2014				2013
	Deferred tax assets:
	Intangible assets	$	34,459			$	42,373
	Capital loss carryforward	169				2,317
	Differences between book basis and tax basis of investments	4,165				3,303
	Stock-based compensation	2,098				2,433
	Other	698				776
	Total deferred tax assets	41,589				51,202
	Valuation allowance on capital loss carryforward	—				(2,148		)
	Total deferred tax assets, net of valuation allowance	41,589				49,054
	Deferred tax liabilities:
	Unrealized net holding gains on investments of available-for-sale securities	902				1,822
	Deferred sales commission	85				137
	Goodwill	81				46
	Other	260				309
	Total deferred tax liabilities	1,328				2,314
	Net deferred tax assets	$	40,261			$	46,740

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Calculation of basic and diluted earnings per share	The following table reflects the calculation of basic and diluted earnings per share:
	(in thousands, except per share amounts)	2014			2013			2012
	Earnings per share – basic:
	Earnings available to common shareholders	$	13,530		$	18,628		$	18,192
	Weighted average shares outstanding	18,275			19,904			20,334
	Earnings per share – basic	$	0.74		$	0.94		$	0.89
	Earnings per share – diluted:
	Earnings available to common shareholders	$	13,530		$	18,628		$	18,192
	Weighted average shares outstanding	18,275			19,904			20,334
	Dilutive impact of restricted stock units	714			448			412
	Weighted average shares outstanding	18,989			20,352			20,746
	Earnings per share – diluted	$	0.71		$	0.92		$	0.88
Schedule of antidilutive securities excluded from computation of earnings per share	The following table shows the number of shares which were excluded from the computation of diluted earnings per share as they were anti-dilutive:
		2014		2013			2012
	Shares of Class A common stock issuable upon an Exchange of Calamos Interests’ ownership in Calamos Investments*	27,916,544		34,594,896			36,735,145
	Restricted stock units	174,523		558,473			—
	Stock options	1,429,167		2,101,568			2,195,414
	Total	29,520,234		37,254,937			38,930,559
	* Number of shares calculated with the value of Calamos Investments determined by using the closing price of our shares as of December 31, 2014 ($13.32), December 31, 2013 ($11.84) and December 31, 2012 ($10.57) as well as assuming said closing prices fully reflect all of CAM's assets; including the application of a 12% discount rate to certain deferred tax assets at each of December 31, 2014, 2013 and 2012. The value of Calamos Investments is then multiplied by Calamos Interests' percentage ownership in Calamos Investments, with the result divided by the applicable year-end closing price. See Note 2, Summary of Significant Accounting Policies - Principles of Consolidation, for a description of certain assets owned by CAM.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Aggregate future minimum payments for operating leases	As of December 31, 2014, the Company’s aggregate future minimum payments for operating leases having initial or non-cancelable terms greater than one year are payable as follows:
		Minimum
	(in thousands)	Payments
	Year ended December 31:
	2015	$	5,433
	2016	4,705
	2017	4,840
	2018	4,953
	2019	5,030
	Thereafter	27,906
	Total minimum lease payments	$	52,867

Regulatory_and_Net_Capital_Req1

Regulatory and Net Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2014
Regulatory Capital Requirements [Abstract]
The net capital, the excess of the required net capital and the net capital ratio	As of December 31, 2014 and 2013, the net capital, the excess of the required net capital and the net capital ratio were as follows:
	(in thousands)	2014		2013
	Net capital	$	1,791	$	6,230
	Excess of required net capital	$	1,003	$	5,394
	Net capital ratio	6.60 : 1.0		2.01 : 1.0

Concentration_Risk_Tables

Concentration Risk (Tables)	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Percentage of revenues derived from services provided to two Company-sponsored open-end funds	For the years ended December 31, 2014, 2013 and 2012, the percentage of revenues derived from services provided to three Company-sponsored open-end funds, the Calamos Growth Fund, the Calamos Growth and Income Fund and the Calamos Market Neutral Fund were as follows:
		2014		2013		2012
	Calamos Growth Fund	18	%	21	%	26	%
	Calamos Growth and Income Fund	14	%	15	%	15	%
	Calamos Market Neutral Fund	14	%	10	%	7	%

Quarterly_Financial_Informatio1

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)
		As of or for the Quarter Ended
		2014								2013
		Dec. 31		Sept. 30		30-Jun		31-Mar		Dec. 31		Sept. 30		30-Jun		31-Mar
	(in millions)
	Assets under management*	$	23,506	$	24,514	$	25,755	$	26,147	$	26,543	$	26,618	$	25,797	$	28,324
	(in thousands, except share data)
	Total revenue	$	60,495	$	63,532	$	63,005	$	63,930	$	66,522	$	64,965	$	66,690	$	70,953
	Total operating expenses	45,868		47,679		46,371		49,854		44,579		49,541		48,286		48,838
	Operating income	$	14,627	$	15,853	$	16,634	$	14,076	$	21,943	$	15,424	$	18,404	$	22,115
	Net income attributable to CAM	$	4,794	$	3,369	$	3,228	$	2,139	$	10,856	$	2,697	$	1,841	$	3,234
	Diluted earnings per share	$	0.25	$	0.18	$	0.17	$	0.11	$	0.54	$	0.13	$	0.09	$	0.16
	Diluted shares outstanding	18,808,798		18,781,856		19,048,456		19,805,828		20,214,360		20,387,651		20,661,447		20,836,996
	*Assets under management do not include assets for which the Company provides model portfolio design and oversight.

Organization_and_Description_o1

Organization and Description of Business (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Calamos Asset Management, Inc.
Corporate Structure [Line Items]
Percentage ownership interest in Calamos Investments LLC	22.20%	22.20%
Calamos Family Partners, Inc.
Corporate Structure [Line Items]
Percentage ownership interest in Calamos Investments LLC	77.80%	77.80%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Principles of Consolidation (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Total deferred tax assets	$40,261,000	$46,740,000
Net Income before income taxes	76,594,000	107,561,000	141,009,000
Interest income on cash and cash equivalent held	3,600,000	2,000,000	230,000
Liabilities of partnership investments	10,117,000	12,378,000
Affiliated Entity
Related Party Transaction [Line Items]
Loan receivable	21,000,000
Calamos Family Partners, Inc.
Related Party Transaction [Line Items]
Percentage ownership interest in Calamos Investments LLC	77.80%	77.80%
Calamos Asset Management, Inc.
Related Party Transaction [Line Items]
Percentage ownership interest in Calamos Investments LLC	22.20%	22.20%
Cash and cash equivalent	79,300,000	78,300,000	67,000,000
Total deferred tax assets	40,261,000	46,740,000	55,300,000
Current income tax receivable, net	2,400,000	2,300,000	606,000
Calamos Investments | Subsidiary
Related Party Transaction [Line Items]
Liabilities of partnership investments	$7,700,000

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Other(Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Restricted cash	$429,000
Conversion basis	one-for-one
Advertising expense	3,800,000	3,700,000	5,400,000
Conversion basis in shares	1
Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	20 years
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	5 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	20 years
Internally Developed Software
Property, Plant and Equipment [Line Items]
Impairment on internally developed software	$0	$199,000	$107,000
Internally Developed Software | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	3 years
Internally Developed Software | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life (in years)	5 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Treasury Stock (Details) (USD $)	12 Months Ended			3 Months Ended	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jun. 13, 2014	Nov. 13, 2013
Class of Stock [Line Items]
Repurchase of common stock by Calamos Investments LLC	$22,470	$13,196
Dividends on shares held	1,200	284
Class A Common Stock
Class of Stock [Line Items]
Repurchase of common stock (in shares)	1,849,729	1,220,330
Number of shares authorized to be repurchased (in shares)					3,000,000	3,000,000
Issuance of common stock (in shares)	294,686	310,080	259,258
Calamos Investments | Class A Common Stock
Class of Stock [Line Items]
Repurchase of common stock (in shares)	1,849,729	1,220,330
Average purchase price of shares (in dollars per share)	$12.15	$10.81
Repurchase of common stock by Calamos Investments LLC	22,500	13,200
Calamos Asset Management, Inc.
Class of Stock [Line Items]
Current income tax receivable, net	2,400	2,300	606	2,400
Percentage ownership interest in Calamos Investments LLC	22.20%	22.20%
Calamos Asset Management, Inc. | Class A Common Stock
Class of Stock [Line Items]
Issuance of common stock (in shares)	294,686	165,524
Issuance of common stock (Class A common shares)	3,400	1,800
Calamos Family Partners, Inc.
Class of Stock [Line Items]
Percentage ownership interest in Calamos Investments LLC	77.80%	77.80%
Treasury Stock
Class of Stock [Line Items]
Repurchase of common stock by Calamos Investments LLC	4,990	2,930
Non-controlling Interest in Calamos Investments LLC (Calamos Interests)
Class of Stock [Line Items]
Repurchase of common stock by Calamos Investments LLC	17,480	10,266
Impact on non-controlling interests as a result of dividends paid to Calamos Investments LLC on repurchased common stock	935	221
Calamos Family Partners, Inc. | Calamos Asset Management, Inc. | Class A Common Stock
Class of Stock [Line Items]
Issuance of common stock (Class A common shares)	2,600	1,400
2014 Share Repurchase Program | Calamos Investments | Common Stock
Class of Stock [Line Items]
Repurchase of common stock (in shares)				70,059
Average purchase price of shares (in dollars per share)				$12.54
Repurchase of common stock by Calamos Investments LLC				879
2013 Share Repurchase Program | Calamos Investments | Class A Common Stock
Class of Stock [Line Items]
Repurchase of common stock (in shares)	1,779,670
Average purchase price of shares (in dollars per share)	$12.13
Repurchase of common stock by Calamos Investments LLC	$21,600				$34,800

Acquisition_Details

Acquisition (Details) (USD $)	0 Months Ended
	Aug. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
	installment
Business Acquisition [Line Items]
Goodwill		$6,380,000	$6,380,000
Black Capital
Business Acquisition [Line Items]
Total purchase price	6,800,000
Paid to selling shareholder at closing	3,400,000
Number of post-closing installments due	2
First installment due after closing (in months)	18 months
Second installment due after closing (in months)	36 months
Goodwill	$6,400,000

Related_Party_Transactions_Fee

Related Party Transactions - Fees Earned from Affiliates (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Investment management fees from:	$198,539	$212,398	$255,823
Distribution fees from open-end funds	49,764	54,068	67,816
CAL
Related Party Transaction [Line Items]
Investment management fees from:	177,809	178,856	207,882
Distribution fees from open-end funds	48,942	53,143	66,604
Portfolio accounting fees from:	2,483	2,489	2,862
CAL | Open-end funds
Related Party Transaction [Line Items]
Investment management fees from:	119,898	124,875	158,040
Portfolio accounting fees from:	1,756	1,810	2,239
CAL | Closed-end funds
Related Party Transaction [Line Items]
Investment management fees from:	57,911	53,981	49,842
Portfolio accounting fees from:	$727	$679	$623

RelatedParty_Transactions_Deta

Related-Party Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Investment management services	$58,000	$85,000	$16,000
1111 Warrenville Road LLC
Related Party Transaction [Line Items]
Lease extension period (in years)	2 years
Lease automatic renewal period (in years)	1 year
Annual base rent and operating expense	774,000	712,000	809,000
2020 Calamos Court LLC
Related Party Transaction [Line Items]
Lease period (in years)	20 years
Annual base rent payments	3,700,000	3,600,000	3,500,000
Percentage increase in annual base rent (as a percent)	3.00%
Primary Business Center LLC
Related Party Transaction [Line Items]
Sublease rental income	277,000	277,000	277,000
2020 Calamos Court Annex LLC
Related Party Transaction [Line Items]
Annual base rent and operating expense	321,000	300,000	289,000
Lease period (in years)	20 years
Percentage increase in annual base rent (as a percent)	3.00%
CF Restaurant Enterprises LLC
Related Party Transaction [Line Items]
Expenses incurred for food and beverage	940,000	956,000	976,000
CityGate Centre 1 LLC
Related Party Transaction [Line Items]
Annual base rent and operating expense	990,000	943,000	922,000
Lease period (in years)	7 years 6 months
Percentage increase in annual base rent (as a percent)	2.50%
JPC Falcon 1109 LLC
Related Party Transaction [Line Items]
Expenses related to use of an airplane for business travel	0	0	589,000
Lease expiry period		26-Apr-13
CFP, CPH and Dragon
Related Party Transaction [Line Items]
Expenses related to hotel accommodations, restaurants and event planning services	$530,000	$533,000	$632,000
Agreements term (in years)	1 year
Notice period to terminate agreement (in days)	30 days

RelatedParty_Transactions_Fees

Related-Party Transactions - Fees Recorded as Expense Allocations (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Total expenses allocated from the Company to affiliates	$849	$808	$869
Net expense allocated from the Company to affiliates	676	657	673
Other receivables	0	0	38
CPH
Related Party Transaction [Line Items]
Total expenses allocated from the Company to affiliates	590	556	606
Accounts receivables (payables)	40	43	1
CFP
Related Party Transaction [Line Items]
Total expenses allocated from the Company to affiliates	243	236	245
Accounts receivables (payables)	-11	9	4
Dragon Leasing Corporation
Related Party Transaction [Line Items]
Total expenses allocated from the Company to affiliates	16	16	18
Accounts receivables (payables)	1	1	41
Calamos
Related Party Transaction [Line Items]
Expense allocated from CPH and CFP to the Company	$173	$151	$196

Investment_Securities_Summary_

Investment Securities - Summary (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Trading securities:
Total investment securities	$339,959	$472,241
Available-for-sale securities:
Available-for-sale securities:
Cost	287,256	415,623
Unrealized Gains	10,377	17,025
Unrealized Losses	-2,890	-700
Fair Value	294,743	431,948
Available-for-sale securities: | Global Growth
Available-for-sale securities:
Cost	142,610	214,811
Unrealized Gains	5,275	11,097
Unrealized Losses	-1,872	-15
Fair Value	146,013	225,893
Available-for-sale securities: | U.S. Growth
Available-for-sale securities:
Cost	64,526	55,109
Unrealized Gains	3,194	2,971
Unrealized Losses	-410	-436
Fair Value	67,310	57,644
Available-for-sale securities: | Value
Available-for-sale securities:
Cost	9,979	9,886
Unrealized Gains	286	315
Unrealized Losses	-171	-243
Fair Value	10,094	9,958
Available-for-sale securities: | Alternative
Available-for-sale securities:
Cost	40,752	35,436
Unrealized Gains	1,283	2,000
Unrealized Losses	-4	0
Fair Value	42,031	37,436
Available-for-sale securities: | Fixed Income/High Yield
Available-for-sale securities:
Cost	17,596	98,834
Unrealized Gains	1	429
Unrealized Losses	-423	-4
Fair Value	17,174	99,259
Available-for-sale securities: | Convertible
Available-for-sale securities:
Cost	10,163	142
Unrealized Gains	15	3
Unrealized Losses	-1	0
Fair Value	10,177	145
Available-for-sale securities: | Multi-Strategy
Available-for-sale securities:
Cost	1,494	1,272
Unrealized Gains	198	130
Unrealized Losses	-9	-2
Fair Value	1,683	1,400
Available-for-sale securities: | Total Funds
Available-for-sale securities:
Cost	287,120	415,490
Unrealized Gains	10,252	16,945
Unrealized Losses	-2,890	-700
Fair Value	294,482	431,735
Available-for-sale securities: | Common stock
Available-for-sale securities:
Cost	136	133
Unrealized Gains	125	80
Unrealized Losses	0	0
Fair Value	261	213
Trading securities: | U.S. Growth
Trading securities:
Cost	52,147	48,539
Unrealized Gains	33	320
Unrealized Losses	-6,964	-8,566
Fair Value	$45,216	$40,293

Investment_Securities_Changes_

Investment Securities - Changes in Investment Securities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale securities:
Proceeds from sales	$293,662	$524,968	$344,911
Gross realized gains on sales	11,024	25,882	28,587
Trading securities:
Unrealized gains (losses)	$1,315	($8,813)	$94

Investment_Securities_Tax_Prov

Investment Securities - Tax (Provision) Benefit on Unrealized Gains (Losses) and Gains (Losses) Reclassified out of AOCI (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes in unrealized gains
Before-Tax Amount	$3,173	$39,630	$19,027
Tax Provision (Benefit)	404	3,793	1,554
After-Tax Amount	2,769	35,837	17,473
Reclassification adjustment for realized gains included in income
Before-Tax Amount	-12,012	-19,732	-20,512
Tax Provision (Benefit)	-1,324	-1,679	-1,676
After-Tax Amount	-10,688	-18,053	-18,836
Other comprehensive income (loss)
Other comprehensive income (loss), before income tax provision (benefit)	-8,839	19,898	-1,485
Tax Provision (Benefit)	-920	2,114	-122
Other comprehensive income (loss), after income tax provision (benefit)	($7,919)	$17,784	($1,363)

Investment_Securities_Narrativ

Investment Securities - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Investments [Abstract]
Investments in Funds	$339,700,000	$472,000,000
Investments in affiliated funds	339,700,000	427,600,000
Aggregate fair value of available-for-sale securities in unrealized loss position	98,100,000	14,000,000
Other than temporary impairment charge	667,000	7,500,000
Unrealized losses, temporary in nature	$2,900,000

Derivative_Assets_and_Liabilit1

Derivative Assets and Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Investment securities	$339,959,000	$472,241,000
Investment and other income (loss)
Derivative [Line Items]
Net loss on derivatives	$1,800,000	$1,900,000	$10,500,000

Partnership_Investments_Detail

Partnership Investments (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2011
Consolidated partnerships:
Cash and cash equivalents	$39,078,000	$35,285,000	$106,796,000	$102,166,000
Due to non-controlling interest in partnership investments	-12,378,000	-10,117,000
Total liabilities	-159,762,000	-109,070,000
Partnership investments	46,425,000	143,723,000
Consolidated partnerships:
Consolidated partnerships:
Securities owned	29,149,000	103,079,000
Cash and cash equivalents	12,208,000	39,205,000
Receivables for securities sold	1,076,000	0
Other current assets	30,000	1,188,000
Exchange-traded option contracts	150,000	201,000
Total assets of consolidated partnerships	42,613,000	143,673,000
Securities sold not yet purchased	-10,670,000	0
Payables for securities purchased	-1,576,000	-2,256,000
Due to non-controlling interest in partnership investments	0	-7,719,000
Accrued expenses and other current liabilities	-76,000	-142,000
Exchange-traded options contracts	-56,000	0
Total liabilities	-12,378,000	-10,117,000
Equity method investment in partnerships	3,812,000	50,000
Consolidated partnerships: | Affiliated Entity
Consolidated partnerships:
Total assets of consolidated partnerships		30,800,000
Calamos International Growth Fund LP
Consolidated partnerships:
Interest in Calamos Global Opportunity Fund LP redeemed	18,700,000
Proceeds from redemption of interest in Calamos Global Opportunity Fund LP	20,000,000
Realized gain from redemption of interest in Calamos Global Opportunity Fund LP	$1,300,000

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	$143,723	$46,425
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	1,209	1,752
Investment securities (Note 5)	337,927	472,241
Securities and derivatives owned by partnership investments (Note 7)	37,083	29,299
Securities sold but not yet purchased by partnership investments (Note 7)		-10,726
Total	373,251	492,566
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Global Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	146,013	225,892
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | U.S. Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	112,526	97,936
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	12,218	9,959
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Alternative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	42,031	37,436
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Fixed Income/High Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	12,174	99,260
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Convertible
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	11,021	145
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Multi-Strategy
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	1,683	1,400
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Total Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	337,666	472,028
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	261	213
Securities and derivatives owned by partnership investments (Note 7)	26,237	29,149
Securities sold but not yet purchased by partnership investments (Note 7)	-2,968	-10,185
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Preferred stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	2,281
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Convertible bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	0
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	0
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Foreign currency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	513
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	7,851
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Exchange-traded put option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	201	150
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Exchange-traded call option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		-56
Recurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		-485
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Investment securities (Note 5)	5,000	0
Securities and derivatives owned by partnership investments (Note 7)	103,770	0
Securities sold but not yet purchased by partnership investments (Note 7)		0
Total	108,770	0
Recurring | Significant Other Observable Inputs (Level 2) | Global Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Alternative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Fixed Income/High Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	5,000	0
Recurring | Significant Other Observable Inputs (Level 2) | Convertible
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Multi-Strategy
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Total Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	5,000	0
Recurring | Significant Other Observable Inputs (Level 2) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	0	0
Securities and derivatives owned by partnership investments (Note 7)	25,166	0
Securities sold but not yet purchased by partnership investments (Note 7)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Preferred stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	3,455
Recurring | Significant Other Observable Inputs (Level 2) | Convertible bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	41,119
Recurring | Significant Other Observable Inputs (Level 2) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	4,821
Recurring | Significant Other Observable Inputs (Level 2) | Foreign currency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	0
Recurring | Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	29,209
Recurring | Significant Other Observable Inputs (Level 2) | Exchange-traded put option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Exchange-traded call option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		0
Recurring | Significant Other Observable Inputs (Level 2) | Exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		0
Recurring | Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	1,209	1,752
Investment securities (Note 5)	342,927	472,241
Securities and derivatives owned by partnership investments (Note 7)	140,853	29,299
Securities sold but not yet purchased by partnership investments (Note 7)		-10,726
Total	482,021	492,566
Recurring | Estimate of Fair Value Measurement | Global Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	146,013	225,892
Recurring | Estimate of Fair Value Measurement | U.S. Growth
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	112,526	97,936
Recurring | Estimate of Fair Value Measurement | Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	12,218	9,959
Recurring | Estimate of Fair Value Measurement | Alternative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	42,031	37,436
Recurring | Estimate of Fair Value Measurement | Fixed Income/High Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	17,174	99,260
Recurring | Estimate of Fair Value Measurement | Convertible
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	11,021	145
Recurring | Estimate of Fair Value Measurement | Multi-Strategy
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	1,683	1,400
Recurring | Estimate of Fair Value Measurement | Total Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	342,666	472,028
Recurring | Estimate of Fair Value Measurement | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities (Note 5)	261	213
Securities and derivatives owned by partnership investments (Note 7)	51,403	29,149
Securities sold but not yet purchased by partnership investments (Note 7)	-2,968	-10,185
Recurring | Estimate of Fair Value Measurement | Preferred stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	5,736
Recurring | Estimate of Fair Value Measurement | Convertible bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	41,119
Recurring | Estimate of Fair Value Measurement | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	4,821
Recurring | Estimate of Fair Value Measurement | Foreign currency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	513
Recurring | Estimate of Fair Value Measurement | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	37,060
Recurring | Estimate of Fair Value Measurement | Exchange-traded put option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and derivatives owned by partnership investments (Note 7)	201	150
Recurring | Estimate of Fair Value Measurement | Exchange-traded call option contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		-56
Recurring | Estimate of Fair Value Measurement | Exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold but not yet purchased by partnership investments (Note 7)		($485)

Fair_Value_Measurements_Narrat

Fair Value Measurements - Narrative (Details) (USD $)	3 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Fair value of investments in open-end funds		$297,000,000	$450,400,000
Carrying value of long-term debt		45,955,000	92,115,000
Fair value of long-term debt		54,200,000	104,400,000
Debt repaid	46,200,000
Carrying value of payment obligation		1,700,000	3,400,000
Fair value of payment obligation		$1,700,000	$3,300,000

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Total costs	$75,391	$77,329
Accumulated depreciation and amortization	-61,145	-60,339
Property and equipment, net	14,246	16,990
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total costs	25,421	27,617
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total costs	32,062	32,062
Computer software
Property, Plant and Equipment [Line Items]
Total costs	$17,908	$17,650

Loans_Payable_Details

Loans Payable (Details) (Margin Loan)	Dec. 31, 2014
Margin Loan
Short-term Debt [Line Items]
Margin loan interest rate effective percentage rate, maximum (as a percent)	1.50%
Percentage of borrowing upon marginal securities, maximum (as a percent)	70.00%

Debt_Narrative_Details

Debt - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jul. 31, 2007	Jul. 15, 2014
Debt Instrument [Line Items]
Total senior unsecured notes	45,955,000	$92,115,000
Current portion of long-term debt	0	46,160,000
Weighted average interest rate on the notes (as a percent)	6.60%
Senior unsecured notes:
Debt Instrument [Line Items]
Debt instrument			375,000,000
6.33% notes due July 15, 2014
Debt Instrument [Line Items]
Total senior unsecured notes	0	46,160,000		46,200,000
6.33% notes due July 15, 2014 | Series 1
Debt Instrument [Line Items]
Debt instrument			197,000,000
Debt instrument interest rate (as a percent)			6.33%
Debt instrument maturity date	15-Jul-14
6.52% notes due July 15, 2017
Debt Instrument [Line Items]
Total senior unsecured notes	22,100,000	22,100,000
6.52% notes due July 15, 2017 | Series 2
Debt Instrument [Line Items]
Debt instrument			85,000,000
Debt instrument interest rate (as a percent)			6.52%
Debt instrument maturity date	15-Jul-17
6.67% notes due July 15, 2019
Debt Instrument [Line Items]
Total senior unsecured notes	23,855,000	23,855,000
6.67% notes due July 15, 2019 | Series 3
Debt Instrument [Line Items]
Debt instrument			$93,000,000
Debt instrument interest rate (as a percent)			6.67%
Debt instrument maturity date	15-Jul-19

Debt_Summary_of_Debt_Details

Debt - Summary of Debt (Details) (USD $)	Dec. 31, 2014	Jul. 15, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Total debt	$45,955		$92,115
Less current portion of long-term debt	0		-46,160
Total long-term debt	45,955		45,955
6.33% notes due July 15, 2014
Debt Instrument [Line Items]
Total debt	0	46,200	46,160
6.52% notes due July 15, 2017
Debt Instrument [Line Items]
Total debt	22,100		22,100
6.67% notes due July 15, 2019
Debt Instrument [Line Items]
Total debt	$23,855		$23,855

Debt_Contractual_Annual_Maturi

Debt - Contractual Annual Maturities (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
2015	$0
2016	0
2017	22,100
2018	0
2019	23,855
Thereafter	0
Total long-term debt	$45,955

Common_Stock_Details

Common Stock (Details)	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Percentage of Class B common stock voting rights	97.40%

Profit_Sharing_Plan_Details

Profit Sharing Plan (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Employer contribution to profit sharing plan	$3.90	$2.50	$4.30

Stock_Based_Compensation_Narra

Stock Based Compensation - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grant (in shares)	10,000,000
Weighted average remaining contractual life (in years)	2 years 11 months
Compensation expense recorded in connection with RSUs and stock options	$6,633,000	$7,025,000	$5,090,000
Stock-based compensation	545,000	577,000	415,000
Total unrecognized compensation expense	16,300,000
Unrecognized compensation expense, expected weighted-average period to be recognized (in years)	2 years 11 months
Additional Paid-in Capital
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized under stock incentive plans credited to additional paid-in capital	1,500,000	1,600,000	1,100,000
RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU awards vesting period (in years)	6 years
Granted (in shares)	897,082	838,663	1,484,723
Estimated fair value of RSU awards	10,700,000	8,900,000	15,900,000
Outstanding, end of period (in shares)	2,567,565	2,584,975	2,612,106	1,818,737
Aggregate intrinsic value	34,200,000
Granted (in shares)	$11.89	$10.66	$10.70
Aggregate intrinsic value and the fair value of RSUs that vested and were exercised	5,100,000	5,000,000	4,100,000
Exercised upon vesting (in shares)	413,298	458,138	332,225
Number of RSUs withheld for taxes (in shares)	118,612	148,058	72,967
Shares withheld for taxes	294,686	310,080	259,258
Number of RSUs converted on a one-for-one basis for shares of company's Class A common stock (in shares)	1
Total intrinsic value and fair value of converted shares	3,600,000	3,400,000	3,200,000
Total tax benefit realized in connection with the vesting of RSUs	$471,000	$443,000	$367,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU awards vesting period (in years)	10 years
Number of RSUs converted on a one-for-one basis for shares of company's Class A common stock (in shares)	1

Stock_Based_Compensation_Restr

Stock Based Compensation - Restricted Stock Unit Activity (Details) (RSU, USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
RSU
Number of Shares
Outstanding, beginning of period	2,584,975	2,612,106	1,818,737
Granted	897,082	838,663	1,484,723
Forfeited	-501,194	-407,656	-359,129
Exercised upon vesting	-413,298	-458,138	-332,225
Outstanding, end of period	2,567,565	2,584,975	2,612,106
Converted during the year	294,686	310,080	259,258
Weighted Average Fair Value of RSUs Granted (in dollars per share)
Outstanding, beginning of period	$11.58	$12.26	$14.75
Granted	$11.89	$10.66	$10.70
Forfeited	$11	$12.14	$13.78
Exercised upon vesting	$12.27	$14.96	$20.11
Outstanding, end of period	$11.69	$11.58	$12.26
Converted during the year	$12.23	$10.87	$12.34

Stock_Based_Compensation_Outst

Stock Based Compensation - Outstanding Stock Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of Shares (in shares)	1,429,167
Options Outstanding, Average Remaining Contractual Life (in years)	2 years
Options Outstanding, Weighted Average Option Price (in dollars per share)	$25.27
Options Exercisable, Number of Shares (in shares)	1,429,167
Options Exercisable, Weighted Average Option Price (in dollars per share)	$25.27
Range of Exercise Prices
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of Shares (in shares)	153,754
Options Outstanding, Average Remaining Contractual Life (in years)	1 year 10 months 24 days
Options Outstanding, Weighted Average Option Price (in dollars per share)	$17.80
Options Exercisable, Number of Shares (in shares)	153,754
Options Exercisable, Weighted Average Option Price (in dollars per share)	$17.80
Range of Exercise Prices, minimum (in dollar per share)	$17.80
Range of Exercise Prices
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of Shares (in shares)	1,019,588
Options Outstanding, Average Remaining Contractual Life (in years)	2 years 2 months 12 days
Options Outstanding, Weighted Average Option Price (in dollars per share)	$23.85
Options Exercisable, Number of Shares (in shares)	1,019,588
Options Exercisable, Weighted Average Option Price (in dollars per share)	$23.85
Range of Exercise Prices, minimum (in dollar per share)	$18
Range of Exercise Prices, maximum (in dollars per share)	$29.11
Range of Exercise Prices
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of Shares (in shares)	255,825
Options Outstanding, Average Remaining Contractual Life (in years)	1 year 1 month 6 days
Options Outstanding, Weighted Average Option Price (in dollars per share)	$35.43
Options Exercisable, Number of Shares (in shares)	255,825
Options Exercisable, Weighted Average Option Price (in dollars per share)	$35.43
Range of Exercise Prices, minimum (in dollar per share)	$35.43

Stock_Based_Compensation_Stock

Stock Based Compensation - Stock Option Activity (Details) (Stock options, USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock options
Number of Shares
Outstanding at beginning of the period	2,101,568	2,195,414	2,345,063
Forfeited/expired	-672,401	-93,846	-149,649
Outstanding at end of the period	1,429,167	2,101,568	2,195,414
Weighted Average Exercise Price (in dollars per share)
Outstanding at beginning of period	$23.42	$23.36	$23.28
Forfeited/expired	$19.49	$21.94	$22.14
Outstanding at end of period	$25.27	$23.42	$23.36

Stock_Based_Compensation_Optio

Stock Based Compensation - Options Exercisable (Details) (Stock options, USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable at end of period (in shares)	1,429,167	1,910,292	1,654,100
Exercisable at the end of period (in dollars per share)	$25.27	$23.76	$24.14

NonOperating_Income_Details

Non-Operating Income (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income and Expenses [Abstract]
Interest income	$160	$257	$385
Interest expense	-4,669	-6,021	-6,017
Net interest expense	-4,509	-5,764	-5,632
Investment income	17,585	29,891	22,073
Dividend income	1,987	5,355	4,557
Miscellaneous other income	341	193	207
Investment and other income	19,913	35,439	26,837
Total non-operating income	$15,404	$29,675	$21,205

Income_Taxes_Income_Tax_Provis

Income Taxes - Income Tax Provision (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	($1,767)	($216)	$2,298
CAM portion	-92	23	185
Calamos Interests portion	178	56	-148
Foreign	15	0	0
Total current income tax provision (benefit)	-1,666	-137	2,335
Deferred:
Federal	6,833	5,867	9,358
State	620	532	875
Total deferred income tax provision	7,453	6,399	10,233
Total income tax provision	$5,787	$6,262	$12,568

Income_Taxes_Narrative_Details

Income Taxes - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]
Valuation allowance	($2,000,000)	($3,000,000)
Current portion of net deferred tax assets	9,194,000	10,165,000
Non-current portions of the net deferred tax assets	31,067,000	36,575,000
Intangible assets	34,459,000	42,373,000
Tax benefit per year created from net deferred income tax asset attributable to intangible assets	7,900,000
Period of tax benefit (in years)	15 years
Tax benefit expiry period	2019
Number of membership units purchased from CFP (in shares)	20,000,000
Number of membership units that qualified for stepped-up in basis (in shares)	17,000,000
Goodwill	6,380,000	6,380,000
Goodwill amortization period (in years)	15 years
Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Capital loss carryforward	456,000
Valuation allowance on tax credit carryforward		$2,100,000

Income_Taxes_Income_Tax_Rate_R

Income Taxes - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Statutory U.S. federal income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefits	2.00%	2.00%	2.00%
Other non-deductible items	0.70%	0.40%	0.40%
Calamos Investments’ state income taxes	1.10%	0.30%	-0.60%
Impact of deferred tax assets valuation allowance	-10.40%	-12.20%	6.10%
Impact of re-measuring certain deferred tax assets	0.00%	0.00%	-2.30%
Impact of expiring employee stock options	2.40%	0.00%	0.00%
Impact on net deferred tax assets from change in statutory income tax rate	-0.60%	-0.30%	0.00%
Effective income tax rate	30.20%	25.20%	40.60%
Calamos Interests state income taxes	-0.90%	-0.20%	0.50%
CAM effective income tax rate	29.30%	25.00%	41.10%

Income_Taxes_Deferred_Income_T

Income Taxes - Deferred Income Taxes (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Intangible assets	$34,459	$42,373
Capital loss carryforward	169	2,317
Differences between book basis and tax basis of investments	4,165	3,303
Stock-based compensation	2,098	2,433
Other	698	776
Total deferred tax assets	41,589	51,202
Valuation allowance on capital loss carryforward	0	-2,148
Total deferred tax assets, net of valuation allowance	41,589	49,054
Deferred tax liabilities:
Unrealized net holding gains on investments of available-for-sale securities	902	1,822
Deferred sales commission	85	137
Goodwill	81	46
Other	260	309
Total deferred tax liabilities	1,328	2,314
Net deferred tax assets	$40,261	$46,740

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings per share – basic:
Earnings available to common shareholders	$4,794	$3,369	$3,228	$2,139	$10,856	$2,697	$1,841	$3,234	$13,530	$18,628	$18,192
Weighted average shares outstanding (in shares)									18,275,246	19,903,507	20,334,299
Earnings per share - basic (in dollars per share)									$0.74	$0.94	$0.89
Earnings per share – diluted:
Earnings available to common shareholders	$4,794	$3,369	$3,228	$2,139	$10,856	$2,697	$1,841	$3,234	$13,530	$18,628	$18,192
Weighted average shares outstanding (in shares)									18,275,246	19,903,507	20,334,299
Dilutive impact of restricted stock units (in shares)									714,000	448,000	412,000
Weighted average diluted shares outstanding (in shares)	18,808,798	18,781,856	19,048,456	19,805,828	20,214,360	20,387,651	20,661,447	20,836,996	18,989,281	20,351,603	20,745,922
Earnings per share - diluted (in dollars per share)	$0.25	$0.18	$0.17	$0.11	$0.54	$0.13	$0.09	$0.16	$0.71	$0.92	$0.88
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive (in shares)									29,520,234	37,254,937	38,930,559
Shares of Class A common stock issuable upon an Exchange of Calamos Interests’ ownership in Calamos Investments | Class A Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive (in shares)									27,916,544	34,594,896	36,735,145
Closing price of shares (in dollars per share)	$13.32				$11.84				$13.32	$11.84	$10.57
Discount rate (as a percent)									12.00%	12.00%	12.00%
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive (in shares)									174,523	558,473	0
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive (in shares)									1,429,167	2,101,568	2,195,414

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Lease expenses	$5,600,000	$5,600,000	$5,200,000
Year ended December 31: [Abstract]
2015	5,433,000
2016	4,705,000
2017	4,840,000
2018	4,953,000
2019	5,030,000
Thereafter	27,906,000
Total minimum lease payments	$52,867,000

Regulatory_and_Net_Capital_Req2

Regulatory and Net Capital Requirements (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Regulatory Capital Requirements [Abstract]
Required ratio of aggregate indebtedness to net capital	15
The net capital, the excess of the required net capital and the net capital ratio [Abstract]
Net capital	$1,791	$6,230
Excess of required net capital	$1,003	$5,394
Net capital ratio	6.6	2.01

Concentration_Risk_Details

Concentration Risk (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Concentration Risk [Line Items]
Number of companies	3
Revenue | Customer Concentration Risk | Calamos Growth Fund
Concentration Risk [Line Items]
Percentage of revenues derived from services provided to two Company-sponsored open-end funds	18.00%	21.00%	26.00%
Revenue | Customer Concentration Risk | Calamos Growth and Income Fund
Concentration Risk [Line Items]
Percentage of revenues derived from services provided to two Company-sponsored open-end funds	14.00%	15.00%	15.00%
Revenue | Customer Concentration Risk | Calamos Market Neutral Fund
Concentration Risk [Line Items]
Percentage of revenues derived from services provided to two Company-sponsored open-end funds	14.00%	10.00%	7.00%

Quarterly_Financial_Informatio2

Quarterly Financial Information (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Assets Under Management	$23,506,000,000	$24,514,000,000	$25,755,000,000	$26,147,000,000	$26,543,000,000	$26,618,000,000	$25,797,000,000	$28,324,000,000	$23,506,000,000	$26,543,000,000
Total revenue	60,495,000	63,532,000	63,005,000	63,930,000	66,522,000	64,965,000	66,690,000	70,953,000	250,962,000	269,130,000	326,676,000
Total operating expenses	45,868,000	47,679,000	46,371,000	49,854,000	44,579,000	49,541,000	48,286,000	48,838,000	189,772,000	191,244,000	206,872,000
Operating income	14,627,000	15,853,000	16,634,000	14,076,000	21,943,000	15,424,000	18,404,000	22,115,000	61,190,000	77,886,000	119,804,000
Net income attributable to CAM	$4,794,000	$3,369,000	$3,228,000	$2,139,000	$10,856,000	$2,697,000	$1,841,000	$3,234,000	$13,530,000	$18,628,000	$18,192,000
Earnings per share - diluted (in dollars per share)	$0.25	$0.18	$0.17	$0.11	$0.54	$0.13	$0.09	$0.16	$0.71	$0.92	$0.88
Weighted average diluted shares outstanding (in shares)	18,808,798	18,781,856	19,048,456	19,805,828	20,214,360	20,387,651	20,661,447	20,836,996	18,989,281	20,351,603	20,745,922

Subsequent_Event_Details

Subsequent Event (Details) (USD $)	12 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 13, 2015
Subsequent Event [Line Items]
Equity distributions paid to non-controlling interests (Calamos Interests)	$71,571	$28,010	$27,692
Subsequent Event
Subsequent Event [Line Items]
Equity distributions paid to non-controlling interests (Calamos Interests)				10,000
Subsequent Event | Ownership Interest In Calamos Investments
Subsequent Event [Line Items]
Equity distributions paid to non-controlling interests (Calamos Interests)				$7,800
Percentage of total distribution				77.80%