Cohen & Steers (CNS) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 25, 2015	Jun. 30, 2014
Entity Information
Entity Registrant Name	COHEN & STEERS INC
Entity Central Index Key	1284812
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		45,387,321
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$845

Consolidated_Statements_of_Fin

Consolidated Statements of Financial Condition (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:
Cash and cash equivalents	$124,938		$128,277
Trading investments	9,509	[1]	15,668	[1]
Equity method investments	28,550		24,724
Available-for-sale investments	21,269		10,449
Accounts receivable	43,392		40,888
Due from broker	1,805		2,906
Property and equipment—net	11,189		9,824
Goodwill	19,120		20,672
Intangible assets—net	1,612		1,701
Deferred income tax asset—net	15,108		14,144
Other assets	4,229		5,673
Total assets	280,721		274,926
Liabilities:
Accrued compensation	28,300		25,214
Income tax payable	4,141		7,575
Deferred rent	5,728		4,344
Other liabilities and accrued expenses	13,964		14,029
Total liabilities	52,133		51,162
Commitments and contingencies
Redeemable noncontrolling interest	607		207
Stockholders’ equity:
Common stock, $0.01 par value; 500,000,000 shares authorized; 48,593,812 and 47,735,793 shares issued at December 31, 2014 and December 31, 2013, respectively	486		477
Additional paid-in capital	489,266		457,138
Accumulated deficit	-142,786		-131,366
Accumulated other comprehensive income, net of tax	-1,582		2,989
Less: Treasury stock, at cost, 3,800,920 and 3,481,942 shares at December 31, 2014 and December 31, 2013, respectively	-117,403		-105,681
Total stockholders’ equity	227,981		223,557
Total liabilities and stockholders’ equity	$280,721		$274,926
[1]	eld as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. (CDF) as of December 31, 2014 and $7,300 attributable to Cohen & Steers Active Commodities Fund, LP (ACOM) as of December 31, 2013.

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
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	48,593,812	47,735,793
Common stock, shares outstanding	44,792,892	44,253,851
Treasury stock, shares	3,800,920	3,481,942
Securities pledged as collateral
Securities pledged as collateral	$650

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Investment advisory and administration fees	$291,744	$271,109	$244,529
Distribution and service fees	14,667	14,359	11,334
Portfolio consulting and other	7,523	12,245	17,690
Total revenue	313,934	297,713	273,553
Expenses:
Employee compensation and benefits	102,732	94,707	88,517
Distribution and service fees	35,470	41,247	41,270
General and administrative	47,337	46,802	39,431
Depreciation and amortization	4,624	5,606	5,562
Amortization of deferred commissions	1,830	3,009	2,341
Total expenses	191,993	191,371	177,121
Operating income	121,941	106,342	96,432
Non-operating income:
Interest and dividend income—net	2,058	2,280	2,530
(Loss) gain from trading investments—net	-1,567	-6,612	4,082
Gain from available-for-sale investments—net	2,041	2,259	1,237
Equity in (losses) earnings of affiliates	-1,955	840	1,050
Other losses	-504	-745	-1,028
Total non-operating income (loss)	73	-1,978	7,871
Income before provision for income taxes	122,014	104,364	104,303
Provision for income taxes	46,280	41,109	36,407
Net income	75,734	63,255	67,896
Less: Net (income) loss attributable to redeemable noncontrolling interest	-224	4,864	-1,779
Net income attributable to common stockholders	$75,510	$68,119	$66,117
Earnings per share attributable to common stockholders:
Basic (in dollars per share)	$1.69	$1.54	$1.51
Diluted (in dollars per share)	$1.65	$1.51	$1.49
Weighted average shares outstanding:
Basic (shares)	44,788	44,272	43,766
Diluted (shares)	45,643	45,083	44,482

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
Net income	$75,734	$63,255	$67,896
Less: Net (income) loss attributable to redeemable noncontrolling interest	-224	4,864	-1,779
Net income attributable to common stockholders	75,510	68,119	66,117
Foreign currency translation (loss) gain (net of tax of $0)	-3,710	1,279	751
Net unrealized gain from available-for-sale investments (net of tax of $0)	1,180	1,628	3,052
Reclassification to statements of operations of gain from available-for-sale investments (net of tax of $0)	-2,041	-2,259	-1,237
Other comprehensive (loss) income	-4,571	648	2,566
Total comprehensive income attributable to common stockholders	$70,939	$68,767	$68,683

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Stockholders' Equity and Redeemable Noncontrolling Interest (USD $)	Total	Common stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss), Net of Tax	Treasury Stock	Total Stockholders' Equity	Redeemable Noncontrolling Interest
In Thousands, except Share data
Beginning balance (redeemable noncontrolling interest) at Dec. 31, 2011								$4,796
Beginning balance at Dec. 31, 2011		462	402,573	-83,063	-225	-89,235	230,512
Beginning balance (shares of common stock, net) at Dec. 31, 2011		43,168,000
Dividends		0	0	-100,943	0	0	-100,943
Issuance of common stock		8	498	0	0	0	506	0
Issuance of common stock, shares		847,000
Repurchase of common stock		0	0	0	0	-8,484	-8,484	0
Repurchase of common stock, shares		-252,000
Tax benefits associated with restricted stock units—net		0	4,223	0	0	0	4,223	0
Issuance of restricted stock units		0	4,594	0	0	0	4,594	0
Amortization of restricted stock units—net		0	17,490	0	0	0	17,490	0
Forfeitures of vested restricted stock units		0	-1	0	0	0	-1	0
Net income (loss)	67,896	0	0	66,117	0	0	66,117	1,779
Other comprehensive income (loss), net of tax	2,566	0	0	0	2,566	0	2,566	0
Distributions to redeemable noncontrolling interest		0	0	0	0	0	0	-8,438
Contributions from redeemable noncontrolling interest	55,132	0	0	0	0	0	0	55,132
Foreign currency translation adjustment on redeemable noncontrolling interest		0	0	0	0	0	0	-81
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2012								53,188
Ending balance at Dec. 31, 2012		470	429,377	-117,889	2,341	-97,719	216,580
Ending balance (shares of common stock, net) at Dec. 31, 2012		43,763,000
Dividends		0	0	-81,596	0	0	-81,596
Issuance of common stock		7	473	0	0	0	480	0
Issuance of common stock, shares		734,000
Repurchase of common stock		0	0	0	0	-7,962	-7,962	0
Repurchase of common stock, shares		-243,000
Tax benefits associated with restricted stock units—net		0	3,146	0	0	0	3,146	0
Issuance of restricted stock units		0	2,689	0	0	0	2,689	0
Amortization of restricted stock units—net		0	21,463	0	0	0	21,463	0
Forfeitures of vested restricted stock units		0	-10	0	0	0	-10	0
Net income (loss)	63,255	0	0	68,119	0	0	68,119	-4,864
Other comprehensive income (loss), net of tax	648	0	0	0	648	0	648	0
Distributions to redeemable noncontrolling interest		0	0	0	0	0	0	-14,242
Contributions from redeemable noncontrolling interest	37,711	0	0	0	0	0	0	37,711
Transfer of redeemable noncontrolling interest in consolidated entity	-71,586	0	0	0	0	0	0	-71,586
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2013								207
Ending balance at Dec. 31, 2013	223,557	477	457,138	-131,366	2,989	-105,681	223,557
Ending balance (shares of common stock, net) at Dec. 31, 2013	44,253,851	44,254,000
Dividends		0	0	-86,930	0	0	-86,930
Issuance of common stock		9	569	0	0	0	578	0
Issuance of common stock, shares		858,000
Repurchase of common stock		0	0	0	0	-11,722	-11,722	0
Repurchase of common stock, shares		-319,000
Tax benefits associated with restricted stock units—net		0	3,676	0	0	0	3,676	0
Issuance of restricted stock units		0	3,045	0	0	0	3,045	0
Amortization of restricted stock units—net		0	24,838	0	0	0	24,838	0
Net income (loss)	75,734	0	0	75,510	0	0	75,510	224
Other comprehensive income (loss), net of tax	-4,571	0	0	0	-4,571	0	-4,571	0
Distributions to redeemable noncontrolling interest		0	0		0	0	0	-8,987
Contributions from redeemable noncontrolling interest	36,278	0	0	0	0	0	0	36,278
Transfer of redeemable noncontrolling interest in consolidated entity	-26,906	0	0	0	0	0	0	-27,115
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2014								607
Ending balance at Dec. 31, 2014	$227,981	$486	$489,266	($142,786)	($1,582)	($117,403)	$227,981
Ending balance (shares of common stock, net) at Dec. 31, 2014	44,792,892	44,793,000

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Stockholders' Equity and Redeemable Noncontrolling Interest (parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Dividends declared per share	$1.88	$1.80	$2.22

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
Cash flows from operating activities:
Net income	$75,734	$63,255	$67,896
Adjustments to reconcile net income to net cash provided by operating activities:
Stock compensation expense	24,931	21,539	17,562
Amortization of deferred commissions	1,830	3,009	2,341
Depreciation and amortization	4,624	5,606	5,562
Deferred rent	1,384	1,954	711
Loss (gain) from trading investments—net	1,567	6,612	-4,082
Equity in losses (earnings) of affiliates	1,955	-840	-1,050
Gain from available-for-sale investments—net	-2,041	-2,259	-1,237
Deferred income taxes	-279	-3,087	-173
Foreign currency (gain) loss	-588	622	572
Changes in operating assets and liabilities:
Accounts receivable	-1,916	2,887	-5,379
Due from broker	-1,137	-8,826	-10,562
Deferred commissions	-1,956	-2,399	-2,981
Trading investments	-51,770	-11,573	-65,347
Other assets	809	1,542	-1,655
Accrued compensation	3,115	-152	3,039
Securities sold but not yet purchased	0	-14,685	6,251
Income tax payable	-3,020	-1,026	4,445
Other liabilities and accrued expenses	1,340	13,693	4,430
Net cash provided by operating activities	54,582	75,872	20,343
Cash flows from investing activities:
Proceeds from redemption of equity method investments	10,881	7,741	811
Purchases of available-for-sale investments	-7,829	-10,195	-20,733
Proceeds from sales of available-for-sale investments	12,699	26,700	25,736
Purchases of property and equipment	-5,916	-6,230	-3,361
Net cash provided by investing activities	9,835	18,016	2,453
Cash flows from financing activities:
Excess tax benefits associated with restricted stock units	2,562	2,025	2,905
Issuance of common stock	491	408	439
Repurchase of common stock	-11,722	-7,962	-8,484
Dividends to stockholders	-84,237	-79,695	-97,208
Distributions to redeemable noncontrolling interest	-8,987	-14,242	-8,438
Contributions from redeemable noncontrolling interest	36,278	37,711	55,132
Net cash used in financing activities	-65,615	-61,755	-55,654
Net (decrease) increase in cash and cash equivalents	-1,198	32,133	-32,858
Effect of foreign exchange rate changes on cash and cash equivalents	-2,141	732	446
Cash and cash equivalents, beginning of the year	128,277	95,412	127,824
Cash and cash equivalents, end of the year	$124,938	$128,277	$95,412

Consolidated_Statements_of_Cas1

Consolidated Statements of Cash Flows (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income taxes paid, net	($46,840)	($43,483)	($29,298)
Fully vested restricted stock units issued	352	789	858
Restricted stock unit dividend equivalents, net of forfeitures	2,693	1,901	3,735
Transfer of redeemable noncontrolling interest in consolidated entity	26,906	71,586
Stock redeemed during period	14,909
MLO
Non-cash increase in equity method investments	22,338
ACOM
Non-cash increase in equity method investments	8,840
RAP
Non-cash increase in equity method investments		$23,519

Basis_of_Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2014
Organization and Description of Business [Abstract]
Organization and Description of Business	Basis of Presentation
	Cohen & Steers, Inc. (CNS) was organized as a Delaware corporation on March 17, 2004. CNS is the holding company for its direct and indirect subsidiaries, including Cohen & Steers Capital Management, Inc. (CSCM), Cohen & Steers Securities, LLC (CSS), Cohen & Steers Asia Limited, Cohen & Steers UK Limited and Cohen & Steers Japan, LLC (collectively, the Company).
	The Company is a leading global investment manager with a long history of innovation and a focus on real assets, including real estate, infrastructure and commodities, along with preferred securities and other income solutions. The Company serves institutional and individual investors around the world. Its clients include Company-sponsored open-end mutual funds and closed-end funds, U.S. and non-U.S. pension plans, endowment funds, foundations and subadvised funds for other financial institutions. The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). The consolidated financial statements set forth herein include the accounts of CNS and its direct and indirect subsidiaries. Intercompany balances and transactions have been eliminated in consolidation.

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
	Accounting Estimates—The preparation of the consolidated financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosures of contingent assets and liabilities at the dates of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. Management believes the estimates used in preparing the consolidated financial statements are reasonable and prudent. Actual results could differ from those estimates.
	Reclassifications—Certain prior year amounts have been reclassified to conform to the current year presentation.
	Consolidation—The Company consolidates operating entities deemed to be voting interest entities if the Company owns a majority of the voting interest. The Company also consolidates any variable interest entities (VIEs) in which the Company is the primary beneficiary. The Company records noncontrolling interests in consolidated subsidiaries for which the Company’s ownership is less than 100 percent. The equity method of accounting is used for investments in affiliates in which the Company’s ownership ranges from 20 to 50 percent, or in instances in which the Company is able to exercise significant influence but not control.
	A VIE is an entity in which either (a) the equity investment at risk is not sufficient to permit the entity to finance its own activities without additional financial support or (b) the group of holders of the equity investment at risk lack certain characteristics of a controlling financial interest. The primary beneficiary is the entity that has the obligation to absorb a majority of the expected losses or the right to receive the majority of the residual returns. Investments and redemptions or amendments to the governing documents of the respective entities could affect an entity's status as a VIE or the determination of the primary beneficiary. The Company assesses whether entities in which it has an interest are VIEs upon initial involvement and at each reporting date. The Company assesses whether it is the primary beneficiary of any VIEs identified by evaluating its economic interests in the entity held either directly by the Company and its affiliates or indirectly through employees. See Note 4 for further discussion about the Company’s investments.
	Cash and Cash Equivalents—Cash equivalents consist of short-term, highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
	Due from Broker—The Company conducts business, primarily through its consolidated seed investments, with brokers for certain of its investment activities. The clearing and custody operations for these investment activities are performed pursuant to agreements with prime brokers. The due from broker balance represents cash and cash equivalents balances at brokers and net receivables and payables for unsettled security transactions.
	Investments—Management of the Company determines the appropriate classification of its investments at the time of purchase and re-evaluates such determination at each statement of financial condition date.
	Investments classified as trading represent securities held within the affiliated funds that the Company consolidates and are measured at fair value based on quoted market prices, market prices obtained from independent pricing services engaged by management or as determined by the Company’s valuation committee. Unrealized gains and losses are recorded as gain (loss) from trading investments—net in the Company’s consolidated statements of operations.
	Investments classified as equity method investments are accounted for using the equity method, under which the Company recognizes its respective share of the investee’s net income or loss for the period. As of December 31, 2014, the Company's equity method investments consisted of interests in affiliated funds which measure their underlying investments at fair value and report a net asset value on a recurring basis. The carrying amounts of these investments approximate their fair value.
	Investments classified as available-for-sale are comprised of equity securities, investment-grade preferred instruments and investments in Company-sponsored open-end mutual funds. These investments are carried at fair value based on quoted market prices or market prices obtained from independent pricing services engaged by management, with unrealized gains and losses, net of tax, reported in accumulated other comprehensive income. The Company periodically reviews each individual security position that has an unrealized loss, or impairment, to determine if that impairment is other than temporary. If the Company believes an impairment of a security position is other than temporary, the loss will be recognized in the Company’s consolidated statements of operations. An other than temporary impairment is presumed to have occurred if the available-for-sale investment has an unrealized loss continuously for 12 or more months.
	From time to time, the affiliated funds consolidated by the Company enter into derivative contracts to gain exposure to the underlying commodities markets or to hedge market and credit risks of the underlying portfolios utilizing options, total return swaps, credit default swaps and futures contracts. These instruments are measured at fair value with gains and losses recorded as gain (loss) from trading investments—net in the Company's consolidated statements of operations. The fair values of these instruments are recorded in other assets or other liabilities and accrued expenses in the Company's consolidated statements of financial condition. As of December 31, 2014, none of the outstanding derivative contracts were subject to a master netting agreement or other similar arrangement.
	Additionally, from time to time, the Company enters into foreign exchange contracts to hedge its currency exposure related to client receivables. These instruments are measured at fair value with gains and losses recorded in other non-operating income in the Company's consolidated statements of operations. The fair values of these contracts are recorded in other assets or other liabilities and accrued expenses in the Company's consolidated statements of financial condition.
	Goodwill and Intangible Assets—Goodwill represents the excess of the cost of the Company’s investment in the net assets of an acquired company over the fair value of the underlying identifiable net assets at the date of acquisition. Goodwill and indefinite lived intangible assets are not amortized but are tested at least annually for impairment by comparing the fair value to their carrying amounts. Finite lived intangible assets are amortized over their useful lives and are tested for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. See Note 3 for further discussion about the Company’s goodwill and intangible assets.
	Redeemable Noncontrolling Interest—Redeemable noncontrolling interest represents third-party interests in the Company's consolidated entities. This interest is redeemable at the option of the investors and therefore is not treated as permanent equity. Redeemable noncontrolling interest is remeasured at redemption value which approximates the fair value at each reporting period.
	Investment Advisory and Administration Fees—The Company earns revenue by providing asset management services to institutional accounts and to Company-sponsored open-end mutual funds and closed-end funds. Investment advisory fees are earned pursuant to the terms of underlying advisory contracts, and are based on a contractual fee rate applied to the assets in the portfolio, net of applicable waivers, if any. The Company also earns administration fees from certain Company-sponsored open-end mutual funds and closed-end funds pursuant to the terms of underlying administration contracts. Administration fees are based on the average assets under management of such funds. Investment advisory and administration fees revenue is recognized as such fees are earned.
	Distribution and Service Fee Revenue—CSS acts as the principal distributor of the Company’s sponsored open-end mutual funds which may offer the following classes: Class A (initial sales load), Class C (back end sales load), Class R (load retirement) and Class Z (no load retirement). Effective May 2007, the Company suspended sales of Class B shares and all remaining Class B shares are expected to convert to Class A shares in 2015. Distribution and service fee revenue is based on the average daily net assets of the funds as detailed below. Distribution and service fee revenue is earned daily and is recorded gross of any third-party distribution and service fee expense for applicable share classes.
	Pursuant to distribution plans with the Company's sponsored open-end mutual funds, CSS receives distribution fees of 25bps for Class A shares, 75bps for Class C shares and 50bps for Class R shares. CSS also receives shareholder servicing fees of 10bps on Class A shares, 25bps on Class C shares and 15bps on Class Z shares, pursuant to shareholder servicing plans with the funds. Effective October 1, 2014, Class Z shares no longer accrued shareholder servicing fees.
	Distribution and Service Fee Expense—Distribution and service fee expense includes distribution fees, service fees and intermediary assistance payments. Distribution and service fee expense is recorded as incurred.
	Distribution fee expense represents payments made to qualified dealers/institutions for (i) assistance in connection with the distribution of the Company's sponsored open-end mutual funds' shares and (ii) for other expenses such as advertising costs and printing and distribution of prospectuses to investors. Such amounts may also be used to pay financial intermediaries for services as specified in the terms of written agreements complying with Rule 12b-1 of the Investment Company Act of 1940 (Rule 12b-1). CSS pays distribution fee expense based on the average daily net assets under management of 25bps on Class A shares, 75bps on Class C shares and 50bps on Class R shares.
	Shareholder servicing fee expense represents payments made to qualified dealers/institutions for shareholder account service and maintenance. These services are provided pursuant to written agreements with such qualified institutions. CSS pays service fee expenses based on the average daily net assets under management of 10bps on Class A shares, 25bps on Class C shares and 15bps on Class Z shares. Effective October 1, 2014, Class Z shares no longer paid shareholder service fees.
	Intermediary assistance payments represent payments to qualified dealers/institutions for activities related to distribution, shareholder servicing and marketing and support of Company-sponsored open-end mutual funds and are incremental to those described above. Intermediary assistance payments may be based on the average assets under management, the number of accounts being serviced, or a combination thereof.
	During the first quarter of 2013 and the third quarter of 2012, the Company made payments of approximately $7.2 million and $14.4 million, respectively, associated with additional compensation agreements entered into in connection with the offering of two closed-end funds. These payments are included in distribution and service fee expense on the accompanying consolidated statements of operations for the years ended December 31, 2013 and December 31, 2012.
	Portfolio Consulting and Other—The Company earns portfolio consulting and other fees by: i) providing portfolio consulting services in connection with model-based strategies accounts; ii) earning a licensing fee for the use of the Company's proprietary indices; and iii) providing portfolio monitoring services related to a number of unit investment trusts. This revenue is earned pursuant to the terms of the underlying contract, and the fee schedules for these relationships vary based on the type of services the Company provides for each relationship. This revenue is recognized as such fees are earned.
	Stock-based Compensation—The Company recognizes compensation expense for the grant-date fair value of awards of equity instruments granted to employees. This expense is recognized over the period during which employees are required to provide service. The Company also estimates forfeitures.
	Income Taxes—The Company records the current and deferred tax consequences of all transactions that have been recognized in the consolidated financial statements in accordance with the provisions of the enacted tax laws. Deferred tax assets are recognized for temporary differences that will result in deductible amounts in future years at tax rates that are expected to apply in those years. Deferred tax liabilities are recognized for temporary differences that will result in taxable income in future years at tax rates that are expected to apply in those years. The Company records a valuation allowance, when necessary, to reduce deferred tax assets to an amount that more likely than not will be realized.
	Currency Translation and Transactions—Assets and liabilities of subsidiaries having non-U.S. dollar functional currencies are translated at exchange rates at the applicable consolidated statement of financial condition date. Revenue and expenses are translated at average exchange rates during the period. The gains or losses resulting from translating non-U.S. dollar functional currency into U.S. dollars are included in the Company's consolidated statements of comprehensive income. Gains or losses resulting from non-U.S. dollar currency transactions are included in other non-operating income in the consolidated statements of operations. The cumulative translation adjustment was $(1,446,000), $2,264,000 and $985,000 as of December 31, 2014, December 31, 2013 and December 31, 2012, respectively.
	Comprehensive Income—The Company reports all changes in comprehensive income in the consolidated statements of comprehensive income. Comprehensive income includes net income or loss attributable to common stockholders, foreign currency translation gain and loss (net of tax), unrealized gain and loss from available-for-sale investments (net of tax) and reclassification to statements of operations of gain and loss from available-for-sale investments (net of tax).
	Recently Issued Accounting Pronouncements—In February 2015, the Financial Accounting Standards Board (FASB) issued new guidance amending the current accounting for consolidation of certain legal entities. These amendments modify the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities, eliminate the presumption that a general partner should consolidate a limited partnership, affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships, and provide a scope exception from consolidation guidance for reporting entities with interests in certain investment funds. This new guidance will be effective for the Company’s first quarter of 2016. The Company is currently evaluating the potential impact on its consolidated financial statements and related disclosures.
	In August 2014, the FASB issued new guidance regarding disclosure of going concern uncertainties in the financial statements. The guidance requires management to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued at each annual and interim reporting period. This new guidance will be effective for the Company’s first quarter of 2017. The Company does not anticipate that the adoption of this new guidance will have a material impact on the Company's consolidated financial statements.
	In May 2014, the FASB issued new guidance which outlined a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The core principle of the revenue model is that an entity recognizes 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 new guidance will be effective for the Company's first quarter of 2017 and requires either a retrospective or a modified retrospective approach to adoption. Early application is prohibited. The Company is currently evaluating the potential impact on its consolidated financial statements and related disclosures, as well as the available transition methods.
	In July 2013, the FASB issued new guidance on the presentation of unrecognized tax benefits when a net operating loss carryforward, a similar tax loss, or a tax credit carryfoward exists. An entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward unless a net operating loss carryforward, a similar tax loss or a tax credit carryforward is not available as of the reporting date or the entity does not intend to use the deferred tax asset for this purpose (provided that the tax law permits a choice). This new guidance was effective for the Company's first quarter of 2014. The adoption of this new guidance did not have a material impact on the Company's consolidated financial statements.
	In June 2013, the FASB issued new guidance which clarifies the characteristics of an investment company and provides guidance for assessing whether an entity is an investment company. From time to time the Company consolidates certain of its affiliated funds which are considered investment companies. The Company retains the specialized investment company accounting for such funds in consolidation. This new guidance was effective for the Company’s first quarter of 2014. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets
	Goodwill and intangible assets recorded in the Company's consolidated statements of financial condition relate to the acquisition of Cohen & Steers Europe SPRL (formerly known as Cohen & Steers Europe S.A.) during 2006. During 2013, the customer contracts of Cohen & Steers Europe SPRL were novated to CSCM or Cohen & Steers UK Limited.
	The following summarizes the changes in the Company's goodwill and intangible assets during the years ended December 31, 2014 and 2013 (in thousands):
		Goodwill				Finite Lived Intangible				Indefinite Lived
						Assets				Intangible Assets
	Balance at January 1, 2013	$	20,122			$	540			$	1,250
	Currency revaluation	550				—				—
	Amortization during 2013	—				(89		)		—
	Balance at December 31, 2013	$	20,672			$	451			$	1,250
	Currency revaluation	(1,552		)		—				—
	Amortization during 2014	—				(89		)		—
	Balance at December 31, 2014	$	19,120			$	362			$	1,250
	The following is a summary of the intangible assets at December 31, 2014 and December 31, 2013 (in thousands):
		Remaining		Gross				Accumulated				Intangible
		Amortization		Carrying				Amortization				Assets, Net
		Period		Amount
		(in months)
	2014
	Amortized intangible assets:
	Client relationships	48		$	1,543			$	(1,181	)		$	362
	Non-amortized intangible assets:
	Mutual fund management contracts	—		1,250				—				1,250
	Total			$	2,793			$	(1,181	)		$	1,612
	2013
	Amortized intangible assets:
	Client relationships	60		$	1,543			$	(1,092	)		$	451
	Non-amortized intangible assets:
	Mutual fund management contracts	—		1,250				—				1,250
	Total			$	2,793			$	(1,092	)		$	1,701
	Amortization expenses related to the intangible assets was approximately $89,000 for each of the years ended December 31, 2014, 2013 and 2012, respectively. Estimated future amortization expense is as follows (in thousands):
	Periods Ending December 31,	Estimated
		Amortization
		Expense
	2015	$	89
	2016	89
	2017	89
	2018	95
	2019	—
	Total	$	362

Investments

Investments	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Investment Holdings	Investments
	The following is a summary of the Company's investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Trading investments	$	9,509		$	15,668
	Equity method investments	28,550			24,724
	Available-for-sale investments	21,269			10,449
	Trading and equity method investments
	The Cohen & Steers Active Commodities Strategy Fund, Inc. (CDF), which was launched by the Company in May 2014, is an open-end mutual fund for which the Company is the investment adviser. As of December 31, 2014, the Company owned the majority of the outstanding voting interest in CDF. Accordingly, the underlying assets and liabilities and results of operations of CDF have been included in the Company's consolidated financial statements with the third-party interests classified as redeemable noncontrolling interest.
	The Cohen & Steers MLP & Energy Opportunity Fund, Inc. (MLO), which was launched by the Company in December 2013, is an open-end mutual fund for which the Company is the investment adviser. The Company owned the majority of the outstanding voting interest in MLO through October 31, 2014. Accordingly, the underlying assets and liabilities and results of operations of MLO had been included in the Company's consolidated financial statements with the third-party interests classified as redeemable noncontrolling interest. As a result of additional third-party subscriptions into the fund, effective November 1, 2014, the Company no longer owned the majority of the outstanding voting interest in MLO, however it was determined that the Company had significant influence over MLO. Accordingly, effective November 1, 2014, the Company began recording its investment in MLO using the equity method of accounting.
	The Cohen & Steers Active Commodities Fund, LP (ACOM), launched by the Company in April 2013, is structured as a partnership. The Company is the investment adviser of ACOM for which it is entitled to receive a management fee. The Company owned all of the voting interest in ACOM through September 30, 2014. Accordingly, the underlying assets and liabilities and results of operations of ACOM had been included in the Company's consolidated financial statements. As a result of third-party investments into the fund, effective October 1, 2014, the Company no longer held a controlling financial interest in ACOM. The Company determined that ACOM was not a VIE as the limited partners, unaffiliated with the Company, have the ability to liquidate the fund with a majority vote. As a result, the Company does not have financial control and ACOM is not consolidated into the Company's consolidated financial statements. As the general partner, the Company has significant influence over the financial decisions of ACOM and therefore records its investment in ACOM using the equity method of accounting. The Company's equity interest in ACOM represents a seed investment to launch the fund, adjusted for the Company's proportionate share of the fund's earnings.
	Cohen & Steers Global Realty Partners III-TE, L.P. (GRP-TE), which had its closing in October 2011, is structured as a partnership. The Company is the general partner and investment adviser of GRP-TE, for which it receives a management fee and is entitled to receive an incentive distribution, if earned. GRP-TE is a VIE and the Company is not the primary beneficiary. As the general partner, the Company has significant influence over the financial decisions of GRP-TE and therefore records its investment using the equity method of accounting. The Company's equity interest in GRP-TE represents a seed investment to launch the fund, adjusted for the Company’s proportionate share of the fund’s earnings. The Company's risk with respect to its investment in GRP-TE is limited to its equity ownership and any uncollected management fees. In conjunction with the launch of GRP-TE, the Company established Cohen & Steers Co-Investment Partnership, L.P. (GRP-CIP), which is used by the Company to fulfill its contractual commitment to co-invest with GRP-TE. See Note 13 for further discussion regarding the Company's co-investment commitment. As of December 31, 2014, the Company owned all of the voting interest in GRP-CIP. Accordingly, the underlying assets and liabilities and results of operations of GRP-CIP have been included in the Company's consolidated financial statements.
	Cohen & Steers Real Assets Fund, Inc. (RAP), which was launched by the Company on January 31, 2012, is an open-end mutual fund for which the Company is the investment adviser. The Company had a controlling financial interest in RAP through July 31, 2013 and therefore, the underlying assets and liabilities and results of operations of RAP had been included in the Company's consolidated financial statements with the third-party interests classified as redeemable noncontrolling interest. During the period of August 1, 2013 through September 30, 2014, as a result of additional third-party subscriptions into the fund, the Company no longer held a controlling financial interest in RAP, however it was determined that the Company had significant influence over RAP. Accordingly, the Company recorded its investment in RAP using the equity method of accounting. Effective September 30, 2014, the Company's ownership interest in RAP fell below 20% and the Company no longer has significant influence over RAP. Accordingly, the Company began recording its investment in RAP as available-for-sale investments.
	Prior to its liquidation in April 2014, the Company owned the majority of the voting interests in Cohen & Steers Global Real Estate Long-Short Fund, L.P. (the Onshore Fund). Accordingly, the underlying assets and liabilities and results of operations of the Onshore Fund had been included in the Company's consolidated financial statements. The Onshore Fund was structured as a partnership and the Company was the general partner and investment adviser of the fund.
	The Cohen & Steers Global Real Estate Long-Short Offshore Fund, L.P. (the Offshore Fund), which was liquidated in April 2014, was structured as a partnership. The Company was the general partner and investment adviser of the Offshore Fund for which it received a management fee and was entitled to receive a performance fee, if earned. The Company determined that the Offshore Fund was not a VIE as the limited partners, unaffiliated with the Company, had the ability to dissolve the fund with a majority vote. As a result, the Company did not have financial control and the Offshore Fund was not consolidated into the Company's consolidated financial statements. As the general partner, the Company had significant influence over the financial decisions of the Offshore Fund and therefore recorded its investment in this fund using the equity method of accounting. The Company’s equity interest in the Offshore Fund represented a seed investment to launch the fund, adjusted for the Company’s proportionate share of the fund’s earnings.
	The following is the condensed statement of financial condition for the aggregate of the Company's equity method investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Total assets	$	166,111		$	163,072
	Total liabilities	5,434			757
	Net assets	160,677			162,315
	The following is the condensed statement of operations for the aggregate of the Company's equity method investments for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31, (1)
		2014			2013			2012
	Total revenue	$	2,896		$	1,142		$	1,524
	Total expenses	2,019			1,985			2,618
	Net realized gain (loss) and net change in unrealized appreciation (depreciation) on investments	(14,827		)	12,833			6,188
	Net (loss) income	$	(13,950	)	$	11,990		$	5,094
	_________________________
	(1)    Amounts are included only for the time in which the investees were accounted for under the equity method.
	The following is a summary of the fair value of trading investments and equity method investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31, 2014						December 31, 2013
		Trading Investments			Equity Method Investments			Trading Investments			Equity Method Investments
	ACOM	$	—		$	7,612		$	7,300		$	—
	CDF	7,000			—			—			—
	GRP-CIP	2,509			—			2,740			—
	GRP-TE	—			111			—			116
	MLO	—			20,827			5,125			—
	Offshore Fund	—			—			—			412
	Onshore Fund	—			—			503			—
	RAP	—			—			—			24,196
	Total	$	9,509		$	28,550		$	15,668		$	24,724
	Gain (loss) from trading investments—net for the years ended December 31, 2014, 2013 and 2012, which represent realized and unrealized gains and losses recorded by the funds the Company consolidates, are summarized below (in thousands):
		Years Ended December 31,
		2014			2013			2012
	ACOM	$	(505	)	$	(484	)	$	—
	CDF	(2,804		)	—			—
	GLIF	—			—			142
	GRP-CIP	151			356			55
	MLO	1,567			155			—
	Onshore Fund	24			495			2,994
	RAP	—			(7,134		)	891
	Total (loss) gain from trading investments—net	$	(1,567	)	$	(6,612	)	$	4,082
	Equity in earnings (losses) of affiliates for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Years Ended December 31,
		2014			2013			2012
	ACOM	$	(1,228	)	$	—		$	—
	GRP-TE	11			13			—
	MLO	(1,511		)	—			—
	Offshore Fund	20			149			1,050
	RAP	753			678			—
	Total equity in earnings (losses) of affiliates	$	(1,955	)	$	840		$	1,050
	Available-for-sale investments
	The following is a summary of the cost, gross unrealized gains, gross unrealized losses and fair value of available-for-sale investments as of December 31, 2014 and December 31, 2013 (in thousands):
	December 31, 2014
	Cost			Gross			Gross			Fair
				Unrealized			Unrealized			Value
				Gains			Losses (1)
Preferred securities	$	1,043		$	54		$	(2	)	$	1,095
Common stocks	5,366			627			(155		)	5,838
Company-sponsored mutual funds	15,010			4			(678		)	14,336
Total available-for-sale investments	$	21,419		$	685		$	(835	)	$	21,269
_________________________
(1)    At December 31, 2014, there were no securities with unrealized losses continuously for a period of more than 12 months.
	December 31, 2013
	Cost			Gross			Gross			Fair
				Unrealized			Unrealized			Value
				Gains			Losses (1)
Preferred securities	$	4,142		$	183		$	(40	)	$	4,285
Common stocks	5,400			698			(132		)	5,966
Company-sponsored mutual funds	197			1			—			198
Total available-for-sale investments	$	9,739		$	882		$	(172	)	$	10,449
_________________________
(1)    At December 31, 2013, there were no securities with unrealized losses continuously for a period of more than 12 months.
The aggregate fair value of available-for-sale investments in an unrealized loss position was approximately $15,875,000 and $1,785,000 at December 31, 2014 and December 31, 2013, respectively.
Unrealized losses on available-for-sale investments as of December 31, 2014 were generally caused by market conditions. When evaluating whether an unrealized loss on an available-for-sale investment is other than temporary, the Company reviews such factors as the extent and duration of the loss, deterioration in the issuer’s credit quality, reduction or cessation of dividend payments and overall financial strength of the issuer. As of December 31, 2014, the Company determined that it had the ability and intent to hold the remaining investments for which no other-than-temporary impairment has occurred until a recovery of fair value. Accordingly, impairment of these investments is considered temporary.
Sales proceeds, gross realized gains and losses from available-for-sale investments for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
	Years Ended December 31,
	2014			2013			2012
Proceeds from sales	$	12,704		$	26,541		$	25,736
Gross realized gains	2,251			2,743			1,918
Gross realized losses	(210		)	(484		)	(681		)

Fair_Value

Fair Value	12 Months Ended
	Dec. 31, 2014
Fair Value [Abstract]
Fair Value	Fair Value
	Codification Topic 820, Fair Value Measurement (ASC 820) specifies a hierarchy of valuation classifications based on whether the inputs to the valuation techniques used in each valuation classification are observable or unobservable. These classifications are summarized in the three broad levels listed below:
	•	Level 1—Unadjusted quoted prices for identical instruments in active markets.
	•	Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable.
	•	Level 3—Valuations derived from valuation techniques in which significant inputs or significant value drivers are unobservable.
	Inputs used to measure fair value might fall in different levels of the fair value hierarchy, in which case the Company defaults to the lowest level input that is significant to the fair value measurement in its entirety. These levels are not necessarily an indication of the risk or liquidity associated with the investments. In determining the appropriate levels, the Company performed a detailed analysis of the assets and liabilities that are subject to ASC 820. Transfers among levels, if any, are recorded at the beginning of the reporting period. There were no transfers between level 1 and level 2 during the year ended ended December 31, 2014.
	The following table presents fair value measurements as of December 31, 2014 (in thousands):
		Level 1			Level 2			Level 3				Total
	Cash equivalents (1)	$	59,281		$	—		$	—			$	59,281
	Trading investments
	Fixed income securities	$	—		$	7,000		$	—			$	7,000
	Limited partnership interests	—			—			2,509				2,509
	Total trading investments	$	—		$	7,000		$	2,509			$	9,509
	Equity method investments	$	20,827		$	7,612		$	111			$	28,550
	Available-for-sale investments
	Preferred securities	$	1,095		$	—		$	—			$	1,095
	Common stocks	5,838			—			—				5,838
	Company-sponsored mutual funds	14,336			—			—				14,336
	Total available-for-sale investments	$	21,269		$	—		$	—			$	21,269
	Derivatives - assets
	Foreign exchange contracts	$	—		$	505		$	—			$	505
	Commodity contracts	234			—			—				234
	Total derivatives - assets	$	234		$	505		$	—			$	739
	Derivatives - liabilities
	Foreign exchange contracts	$	—		$	12		$	—			$	12
	Commodity contracts	754			—			—				754
	Total derivatives - liabilities	$	754		$	12		$	—			$	766
	_________________________
	(1) Comprised of investments in actively traded money market funds measured at net asset value.
	Trading investments classified as level 2 in the above table were primarily comprised of investments in United States Treasury Bills carried at amortized cost, which approximates fair value.
	Trading investments classified as level 3 in the above table were comprised of limited partnership interests which represent the Company's co-investments through GRP-CIP, which along with the Company's interest in GRP-TE, represent the Company's collective ownership interests in limited partnership vehicles that invest in non-registered real estate funds which are valued based on the net asset values of the underlying funds and private equity vehicles that invest directly in real estate which are generally valued using a discounted cash flow model.
	Equity method investments classified as level 2 in the above table represent the carrying amount of the Company's partnership interest in ACOM, which approximates its fair value based on the fund's net asset value. ACOM invests in exchange-traded commodity futures contracts and other commodity related derivatives. The Company has the ability to redeem its investment in the fund monthly at net asset value per share with prior written notice of 15 days and there are no significant restrictions to redemption.
	Equity method investments classified as level 3 in the above table represent the carrying amount of the Company's partnership interests in GRP-TE, which approximate its fair value based on the fund's net asset value. GRP-TE invests in non-registered real estate funds and in private equity vehicles that invest directly in real estate. As of December 31, 2014, the Company did not have the ability to redeem its investment in GRP-TE.
	The following table presents fair value measurements as of December 31, 2013 (in thousands):
		Level 1			Level 2			Level 3				Total
	Cash equivalents (1)	$	61,551		$	—		$	—			$	61,551
	Trading investments
	Common stocks	$	5,125		$	—		$	503			$	5,628
	Fixed income securities	—			7,300			—				7,300
	Limited partnership interests	—			—			2,740				2,740
	Total trading investments	$	5,125		$	7,300		$	3,243			$	15,668
	Equity method investments	$	24,196		$	—		$	528			$	24,724
	Available-for-sale investments
	Preferred securities	$	960		$	—		$	3,325			$	4,285
	Common stocks	5,966			—			—				5,966
	Company-sponsored mutual funds	198			—			—				198
	Total available-for-sale investments	$	7,124		$	—		$	3,325			$	10,449
	Derivatives - assets
	Foreign exchange contracts	$	—		$	398		$	—			$	398
	Commodity contracts	305			—			—				305
	Total derivatives - assets	$	305		$	398		$	—			$	703
	Derivatives - liabilities
	Commodity contracts	$	275		$	—		$	—			$	275
	Total derivatives - liabilities	$	275		$	—		$	—			$	275
	_________________________
	(1) Comprised of investments in actively traded money market funds measured at net asset value.
	Trading investments classified as level 2 in the above table were primarily comprised of investments in United States Treasury Bills carried at amortized cost, which approximates fair value.
	Trading investments classified as level 3 in the above table were comprised of investments in the common stock of a privately held bank holding company and limited partnership interests. The investments in the common stock of a privately held bank holding company were valued by the Company's valuation committee using a market approach which utilized market multiples derived from a set of comparable public companies. The limited partnership interests represent the Company's co-investments through GRP-CIP. The methodology used to value the investments held by GRP-CIP was changed during the year ended December 31, 2013 as the transaction cost was no longer a reasonable approximation of value due to the passage of time.
	Equity method investments classified as level 3 in the above table represent the carrying amount of partnership interests in the Offshore Fund and GRP-TE, which approximate their fair value based on each fund's net asset value. The Offshore Fund made long and short investments in listed real estate equity securities to maximize absolute and risk-adjusted returns with modest volatility. As of December 31, 2013, the Company did not have the ability to redeem its investment in either fund.
	Available-for-sale investments classified as level 3 in the above table were comprised of an auction rate preferred security of a closed-end fund which was measured at fair value using a third-party pricing service which utilized a combination of a market approach based on the quoted prices for identical or similar instruments in markets that are not active and an income approach in which the expected cash flows of the securities were discounted back to the measurement date. The Company reviewed the fair value provided by the pricing service and confirmed its understanding of the methodology utilized.
	The following table summarizes the changes in level 3 investments measured at fair value on a recurring basis for the years ended December 31, 2014 and 2013 (in thousands):
		Trading						Equity Method Investments				Available-for-sale investments
		Investments
		Common Stocks			Limited Partnership Interests			GRP-TE/Offshore Fund				Preferred Securities
Balance at January 1, 2013	$	1,168		$	2,142		$	89			$	3,080
Purchases / contributions	—			393			15				—
Sales / distributions	(419		)	(151		)	(7,066		)		—
Realized (losses) gains	(211		)	11			—				—
Unrealized (losses) gains (1)	(35		)	345			54				245
Transfers into level 3	—			—			7,436			(2)	—
Balance at December 31, 2013	$	503		$	2,740		$	528			$	3,325
Purchases / contributions	—			625			18				—
Sales / distributions	(527		)	(721		)	(457		)		(4,000		)
Realized gains	24			64			—				675
Unrealized (losses) gains (1)	—			(199		)	22				—
Transfers into (out of) level 3	—			—			—				—
Balance at December 31, 2014	$	—		$	2,509		$	111			$	—
_________________________
-1	Pertains to unrealized gains (losses) from securities held at December 31, 2014 and 2013, respectively.
-2	Transferred from level 2 to level 3 during the year ended December 31, 2013 due to the imposition of redemption restrictions on the Company's investment in connection with the winding down of the operations of the Offshore Fund.
Realized gains (losses) from investments classified as trading investments, equity method investments and available-for-sale investments in the above table were recorded as gain (loss) from trading investments, equity in earnings (losses) of affiliates and gain (loss) from available-for-sale investments, respectively, in the Company's consolidated statements of operations. Unrealized gains (losses) from investments classified as trading investments and equity method investments in the above table were recorded as gain (loss) from trading investments and equity in earnings (losses) of affiliates, respectively, in the Company's consolidated statements of operations. Unrealized gains (losses) from available-for-sale investments in the above table were recorded as unrealized gain (loss) from available-for-sale investments in the Company's consolidated statements of comprehensive income.
Valuation Techniques
In certain instances, debt and equity securities are valued on the basis of prices from an orderly transaction between market participants provided by reputable brokers/dealers or pricing services. In determining the value of a particular investment, pricing services may use information with respect to transactions in such investments, broker quotes, pricing matrices, market transactions in comparable investments and various relationships between investments. As part of its independent price verification process, the Company selectively performs detailed reviews of valuations provided by broker/dealers or pricing services.
Foreign exchange contracts are valued by interpolating a value using the spot foreign exchange rate and forward points (based on the spot rate and currency interest rate differentials), which are all inputs that are observable in active markets (level 2).
In the absence of observable market prices, the Company values its investments using valuation methodologies applied on a consistent basis. For some investments, little market activity may exist; management's determination of fair value is then based on the best information available in the circumstances, and may incorporate management's own assumptions and involves a significant degree of judgment, taking into consideration a combination of internal and external factors. Such investments are valued on a quarterly basis, taking into consideration any changes in key inputs and changes in economic and other relevant conditions, and valuation models are updated accordingly. The valuation process also includes a review by the Company's valuation committee which is comprised of senior members from various departments within the Company, including investment management. The valuation committee provides independent oversight of the valuation policies and procedures.
The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2014 were:
	Fair Value			Fair Value		Significant	Input /
	(in thousands)			Methodology		Unobservable Inputs	Range
Limited partnership interests - direct investments in real estate	$	1,465		Discounted cash flows		Discount rate	9% - 15%
						Exit capitalization rates	8% - 8.5%
						Market rental rates	$15.00 - 17.00 psf
The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2013 were:
	Fair Value			Fair Value		Significant	Input /
	(in thousands)			Methodology		Unobservable Inputs	Range
Common shares of privately-held company	$	503		Market comparable companies		Price / tangible book ratio	1.48x
						Liquidity discount	33%
Limited partnership interests - direct investments in real estate	$	2,101		Discounted cash flows		Discount rate	9% - 15%
						Exit capitalization rates	8.5% - 9%
						Market rental rates	$15.00 - 16.25 psf
Changes in the significant unobservable inputs in the tables above may result in a materially higher or lower fair value measurement. The disclosure in the above tables excludes the Company's ownership interests in limited partnership vehicles which are valued based on the net asset values of the underlying funds. The disclosure in the above table as of December 31, 2013 also excludes auction rate preferred securities for which fair value is based on unobservable but non-quantitative inputs. Such items include financial instruments for which the determination of fair value is based on unadjusted quotations provided by a third-party pricing service.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2014
Derivatives [Abstract]
Derivatives	Derivatives
	The following is a summary of the notional and fair value of the derivative financial instruments. The notional amount represents the absolute value amount of all outstanding derivative contracts as of December 31, 2014 and December 31, 2013 (in thousands):
		31-Dec-14
		Assets						Liabilities
		Notional			Fair Value			Notional			Fair Value
	Total foreign exchange contracts	$	11,349		$	505		$	222		$	12
	Total commodity contracts	6,095			234			8,977			754
	Total derivatives	$	17,444		$	739		$	9,199		$	766
		31-Dec-13
		Assets						Liabilities
		Notional			Fair Value			Notional			Fair Value
	Total foreign exchange contracts	$	10,853		$	398		$	—		$	—
	Total commodity contracts	8,115			305			5,738			275
	Total derivatives	$	18,968		$	703		$	5,738		$	275
	Cash included in due from broker in the consolidated statement of financial condition of approximately $422,000 and $2,110,000 as of December 31, 2014 and December 31, 2013, respectively, was held as collateral for futures contracts. Securities included in trading investments in the consolidated statement of financial condition of approximately $650,000 and $7,300,000 as of December 31, 2014 and December 31, 2013, respectively, were held as collateral for futures contracts.
	Gains and losses from derivative financial instruments for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Equity contracts	$	—		$	(584	)	$	125
	Foreign exchange contracts	95			(218		)	686
	Commodity contracts	(3,280		)	(3,689		)	(517		)
	Credit contracts	—			(21		)	(38		)
	Total derivatives	$	(3,185	)	$	(4,512	)	$	256

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment
	The following is a summary of property and equipment as of December 31, 2014 and 2013 (in thousands):
		December 31,
		2014			2013
	Equipment	$	6,536		$	8,606
	Furniture and fixtures	2,024			3,487
	Software	15,479			13,405
	Leasehold improvements	9,358			11,374
	Subtotal	33,397			36,872
	Less: Accumulated depreciation and amortization	(22,208		)	(27,048		)
	Property and equipment, net	$	11,189		$	9,824
	Depreciation and amortization expense related to property and equipment was $4,535,000, $5,517,000 and $5,473,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	Depreciation and amortization expense is recorded using the straight-line method over the estimated useful lives of the related assets which range from 3-7 years.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	Basic earnings per share is calculated by dividing net income attributable to common stockholders by the weighted average shares outstanding. Diluted earnings per share is calculated by dividing net income attributable to common stockholders by the total weighted average shares of common stock outstanding and common stock equivalents. Common stock equivalents are comprised of dilutive potential shares from restricted stock unit awards. Common stock equivalents are excluded from the computation if their effect is anti-dilutive. Diluted earnings per share are computed using the treasury stock method.
	No anti-dilutive common stock equivalents were excluded from the computation for the years ended December 31, 2014, 2013 and 2012.
	The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations for the years ended December 31, 2014, 2013 and 2012 (in thousands, except per share data):
		Years Ended December 31,
		2014			2013		2012
	Net income	$	75,734		$	63,255	$	67,896
	Less: Net (income) loss attributable to redeemable noncontrolling interest	(224		)	4,864		(1,779		)
	Net income attributable to common stockholders	$	75,510		$	68,119	$	66,117
	Basic weighted average shares outstanding	44,788			44,272		43,766
	Dilutive potential shares from restricted stock units	855			811		716
	Diluted weighted average shares outstanding	45,643			45,083		44,482
	Basic earnings per share attributable to common stockholders	$	1.69		$	1.54	$	1.51
	Diluted earnings per share attributable to common stockholders	$	1.65		$	1.51	$	1.49

StockBased_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
	Amended and Restated Stock Incentive Plan
	The Amended and Restated Cohen & Steers, Inc. Stock Incentive Plan (the SIP) provides for the issuance of Restricted Stock Units (RSUs), stock options and other stock-based awards for a period of up to ten years to eligible employees and directors. A total of 16.0 million shares of common stock may be granted under the SIP. At December 31, 2014, RSUs with respect to approximately 12.7 million shares of common stock were issued. Total compensation cost related to unvested RSUs not yet recognized was approximately $34,343,000 at December 31, 2014 and is expected to be recognized over approximately the next three years.
	Restricted Stock Units
	Vested Restricted Stock Unit Grants
	The Company has granted awards of vested RSUs to the independent directors of the Company pursuant to the SIP. The directors are entitled to receive delivery of the underlying common stock on the third anniversary of the date of the grant. Dividends declared during the delayed delivery period are paid to the directors in cash. From time to time, the Company grants awards of vested RSUs to certain employees pursuant to the SIP. These grants are usually delivered pro-rata over four years. At December 31, 2014, vested RSUs with respect to approximately 28,000 shares of common stock were outstanding pursuant to these grants. In connection with the grant of these vested RSUs, the Company recorded non-cash stock-based compensation expense of approximately $352,000, $300,000 and $326,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	The following table sets forth activity relating to the Company's granted awards of vested RSUs under the SIP for awards to the independent directors and certain employees (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	45		$	19.9
	Granted	10		31.77
	Delivered	(21	)	13.79
	Balance at December 31, 2012	34		27.46
	Granted	9		33.83
	Delivered	(14	)	22.79
	Balance at December 31, 2013	29		31.47
	Granted	9		39.67
	Delivered	(10	)	29.12
	Balance at December 31, 2014	28		34.93
	Unvested Restricted Stock Unit Grants
	The Company grants awards of unvested RSUs to certain employees pursuant to the SIP. The fair value at the date of grant is expensed on a straight-line basis over the applicable service periods. Except in circumstances where a dividend is determined to be an extraordinary dividend in the sole discretion of the Company's Compensation Committee (in which case dividend equivalents are accrued on such RSUs in the form of additional unvested RSUs), dividends are not paid to the holders of such unvested RSUs. At December 31, 2014, RSUs with respect to approximately 690,000 shares of common stock were outstanding pursuant to these grants. Amortization expense related to the unearned stock-based compensation, net of forfeitures, was approximately $8,590,000, $8,491,000 and $7,328,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	The following table sets forth activity relating to the Company's granted awards under the above mentioned plans (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	1,279		$	22.21
	Granted	100		32.34
	Delivered	(346	)	23.57
	Forfeited	(54	)	20.75
	Balance at December 31, 2012	979		22.85
	Granted	305		34.2
	Delivered	(307	)	21.95
	Forfeited	(27	)	25.28
	Balance at December 31, 2013	950		26.72
	Granted	110		37.33
	Delivered	(361	)	24.45
	Forfeited	(9	)	25.69
	Balance at December 31, 2014	690		29.62
	Incentive Bonus Plans for Employees of the Company
	The Company has implemented a program for employees which, based upon compensation levels, automatically pays a portion of their year-end bonuses in the form of unvested RSUs (Mandatory Program). Prior to performance year 2013, employees could also elect to defer, on a pre-tax basis, an additional portion of their year-end bonus in the form of vested RSUs (Voluntary Program). These RSUs were issued pursuant to the SIP. Prior to performance year 2013, under both plans, the Company matched a predetermined amount of the employee contribution in the form of unvested RSUs. Dividend equivalents are accrued on the deferred compensation awards and the matches in the form of additional unvested RSUs. The RSUs under the Mandatory Program, including the Company match, will vest and be delivered pro-rata over four years. The dividend equivalents issued under the Mandatory Program vest and will be delivered four years after the date of the associated original grant. The RSUs granted under the Voluntary Program vest immediately at the date of grant and will be delivered three years after the date of grant. The Company match and dividend equivalents under the Voluntary Program vest and will be delivered three years after the date of the original grant. The fair value at the date of grant of the RSUs under the Mandatory Program and the matching under both programs is expensed on a straight-line basis. On May 8, 2012, the Company discontinued the company match on amounts deferred under the Mandatory Program. All historical grants made pursuant to the company match on amounts deferred under the Mandatory Program will continue to vest and be delivered in accordance with the previous schedule. Further, on May 8, 2012, the Company discontinued the Voluntary Program, commencing with performance year 2013. All historical grants made pursuant to the Voluntary Program, as well as the Company match on such grants, will continue to vest and/or be delivered in accordance with the previous schedule. All employees that made an election to voluntarily defer a portion of their 2012 year-end bonus were permitted to defer such optional deferred amount, and received a matching contribution from the company on such optional deferred amount.
	As of December 31, 2014, approximately 1,412,000 and 42,000 RSUs under the Mandatory Program and Voluntary Program, respectively, including matching and dividend equivalents, were outstanding. In connection with the grant of the vested RSUs issued under the Voluntary Program, the Company recorded a non-cash stock-based compensation expense, including amortization on the matching component, of approximately $116,000, $113,000, and $577,000 for the years ended December 31, 2014, 2013 and 2012, respectively. Amortization expense, net of forfeitures, related to the unearned stock-based compensation of the Mandatory Program, including the matching component, was approximately $16,178,000, $12,863,000 and $10,069,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	The following table sets forth activity relating to the Company's incentive bonus plans, including Company match and dividend equivalents (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	1,132		$	25.88
	Granted	692		33.38
	Delivered	(464	)	24.72
	Forfeited	(46	)	30.88
	Balance at December 31, 2012	1,314		30.07
	Granted	587		33.55
	Delivered	(400	)	27.79
	Forfeited	(70	)	32.13
	Balance at December 31, 2013	1,431		32.03
	Granted	522		36.67
	Delivered	(472	)	30.84
	Forfeited	(27	)	34.29
	Balance at December 31, 2014	1,454		34.04
	Employee Stock Purchase Plan
	Pursuant to the Amended and Restated Employee Stock Purchase Plan (ESPP), the Company allows eligible employees, as defined in the ESPP, to purchase common stock at a 15% discount from market value with a maximum of $25,000 in annual aggregate purchases by any one individual. The number of shares of common stock authorized for purchase by eligible employees was 600,000. For the years ended December 31, 2014, 2013 and 2012, approximately 14,000, 13,000 and 16,000 shares, respectively, had been purchased by eligible employees through the ESPP. For the years ended December 31, 2014, 2013 and 2012, the Company recorded a non-cash stock-based compensation expense of approximately $87,000, $72,000 and $76,000, respectively, which represents the discount on the shares issued pursuant to this plan. The ESPP will terminate upon the earliest to occur of the following: (1) termination of the ESPP by the board of directors, or (2) issuance of all of the shares reserved for issuance under the ESPP.

401k_and_ProfitSharing_Plan

401(k) and Profit-Sharing Plan	12 Months Ended
	Dec. 31, 2014
Compensation Related Costs [Abstract]
401 (k) and Profit-Sharing Plan	401(k) and Profit-Sharing Plan
	The Company sponsors a profit-sharing plan (the Plan) covering all employees who meet certain age and service requirements. Subject to limitations, the Plan permits participants to defer up to 100% of their compensation pursuant to Section 401(k) of the Internal Revenue Code. Employee contributions are matched by the Company at $0.50 per $1.00 deferred. The Plan also allows the Company to make discretionary contributions, which are integrated with the taxable wage base under the Social Security Act. No discretionary contributions were made for the years ended December 31, 2014, 2013 and 2012.
	Forfeitures occur when participants terminate employment before becoming entitled to their full benefits under the Plan. Forfeited amounts are used to reduce the Company's contributions to the Plan or to pay Plan expenses. Forfeitures for the years ended December 31, 2014, 2013 and 2012 totaled approximately $83,000, $176,000 and $72,000, respectively.
	Matching contributions, net of forfeitures, to the Plan totaled approximately $1,074,000, $1,462,000 and $1,110,000 for the years ended December 31, 2014, 2013 and 2012, respectively.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions
	The Company is an investment adviser to, and has administrative agreements with, affiliated funds for which certain employees are officers and/or directors. The following table sets forth the amount of revenue the Company earned from these affiliated funds for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31,
		2014			2013		2012
	Investment advisory and administration fees	$	210,316		$	190,058	$	155,931
	Distribution and service fees	14,667			14,359		11,334
		$	224,983		$	204,417	$	167,265
	For the year ended December 31, 2012, the Company had investment advisory agreements with certain affiliated closed-end funds, pursuant to which the Company contractually waived approximately $299,000 of advisory fees it was otherwise entitled to receive. There were no such fees waived for the years ended December 31, 2014 and 2013. These investment advisory agreements contractually required the Company to waive a portion of the advisory fees the Company otherwise would charge for up to 10 years from the respective fund's inception date. The board of directors of these mutual funds must approve the renewal of the advisory agreements each year, including any reduction in advisory fee waivers scheduled to take effect during that year. As of December 31, 2014, there were no additional scheduled reductions in advisory fee waivers for any fund.
	Sales proceeds, gross realized gains, gross realized losses and dividend income from available-for-sale investments in Company-sponsored mutual funds for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Years Ended December 31,
		2014			2013		2012
	Proceeds from sales	$	192		$	10,715	$	103
	Gross realized gains	—			615		4
	Gross realized losses	(3		)	—		—
	Dividend income	390			9		3
	The Company has agreements with certain affiliated open-end mutual funds and closed-end funds to reimburse certain fund expenses. For the years ended December 31, 2014, 2013 and 2012, expenses of approximately $9,218,000, $9,332,000 and $6,345,000, respectively, were incurred by the Company pursuant to these agreements and are included in general and administrative expenses.
	Included in accounts receivable at December 31, 2014 and 2013 are receivables due from Company-sponsored mutual funds of approximately $19,750,000 and $18,026,000, respectively.

Regulatory_Requirements

Regulatory Requirements	12 Months Ended
	Dec. 31, 2014
Regulatory Capital Requirements [Abstract]
Regulatory Requirements	Regulatory Requirements
	CSS, a registered broker/dealer in the U.S., is subject to the SEC’s Uniform Net Capital Rule 15c3-1 (the Rule), which requires that broker/dealers maintain a minimum level of net capital, as prescribed under the Rule. As of December 31, 2014, CSS had net capital of approximately $1,440,000, which exceeded its requirements by approximately $1,281,000. The Rule also provides that equity capital may not be withdrawn or cash dividends paid if the resulting net capital of a broker/dealer is less than the amount required under the Rule and requires prior notice to the SEC for certain withdrawals of capital.
	CSS does not carry customer accounts and is exempt from the SEC’s Rule 15c3-3 pursuant to provisions (k)(1) and (k)(2)(i) of such rule.
	Certain of the non-U.S. subsidiaries of the Company (collectively, the Foreign Regulated Entities) are regulated outside the U.S. by the Hong Kong Securities and Futures Commission and the United Kingdom Financial Conduct Authority. As of December 31, 2014, the Foreign Regulated Entities had aggregate regulatory capital of approximately $58,806,000, which exceeded requirements by approximately $56,611,000. Effective December 31, 2013, Cohen & Steers Europe SPRL requested, and was granted, a withdrawal of its investment services license with the Belgium Financial Services and Markets Authority.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure	Commitments and Contingencies
	The Company leases office space under noncancelable operating leases expiring at various dates through January 2024. On June 29, 2012, the Company extended the lease for its corporate headquarters in New York City for an added 10 year period through January 2024. The Company also leases certain computer and office equipment under noncancelable operating leases expiring at various dates through December 2019. The aggregate minimum future payments under the leases are as follows (in thousands):
	Years Ended December 31,	Operating Leases
	2015	$	11,354
	2016	11,025
	2017	10,213
	2018	9,838
	2019	10,580
	Thereafter	42,859
		$	95,869
	Rent expense charged to operations, including escalation charges for real estate taxes and other expenses, totaled approximately $10,103,000, $10,067,000 and $8,535,000 for the years ended December 31, 2014, 2013 and 2012, respectively. Sublease rental income received for the years ended December 31, 2014, 2013 and 2012 was approximately $70,000, $876,000 and $1,025,000, respectively.
	From time to time, the Company is involved in legal matters relating to claims arising in the ordinary course of business. There are currently no such matters pending that the Company believes could have a material adverse effect on its consolidated results of operations, cash flows or financial position.
	The Company periodically commits to fund a portion of the equity in certain of its sponsored investment products. The Company has committed to co-invest up to $5.1 million alongside GRP-TE, a portion of which is made through GRP-TE and the reminder of which is made through GRP-CIP for up to 12 years through the life of GRP-TE. As of December 31, 2014, the Company has funded approximately $3.2 million with respect to this commitment. The actual timing of the funding of this commitment is currently unknown, as the drawdown of the Company's commitment is contingent on the timing of drawdowns by the underlying funds and co-investments in which GRP-TE invests. The unfunded commitment was not recorded on the Company's consolidated statements of financial condition as of December 31, 2014.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The provision for income taxes for the years ended December 31, 2014, 2013 and 2012 includes U.S. federal, state, local and foreign taxes. The effective tax rate for the year ended December 31, 2014 was approximately 38%. The effective tax rate of approximately 37.6% for the year ended December 31, 2013 included discrete items, the most significant of which was attributable to the launch costs for Cohen & Steers MLP Income and Energy Opportunity Fund, Inc., a closed-end fund. Excluding the discrete items, the effective tax rate for the year ended December 31, 2013 was approximately 38%. The effective tax rate of approximately 35.5% for the year ended December 31, 2012 included discrete items, the most significant of which was attributable to the launch costs for Cohen & Steers Limited Duration Preferred and Income Fund, Inc., a closed-end fund. Excluding the discrete items, the effective tax rate for the year ended December 31, 2012 was approximately 36%.
	The Company does not provide for deferred taxes on the excess of the financial reporting basis over the tax basis in its investments in foreign subsidiaries that are essentially permanent in duration. That excess totaled approximately $73,425,000 as of December 31, 2014. The determination of the additional deferred taxes that have not been provided is not practicable because of the complexities of the hypothetical calculation.
	The income before provision for income taxes and provision for income taxes for the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Years Ended December 31,
		2014				2013				2012
	Income before provision for income taxes - U.S.	$	108,452			89,963				89,828
	Income before provision for income taxes - Non-U.S.	13,562				14,401				14,475
	Total income before provision for income taxes	$	122,014			$	104,364			$	104,303
	Current taxes:
	U.S. federal	$	38,711			$	36,490			$	29,723
	State and local	4,966				5,025				3,754
	Non-U.S.	2,882				2,681				3,103
		46,559				44,196				36,580
	Deferred taxes:
	U.S. federal	(96		)		(2,754		)		(92		)
	State and local	(12		)		(379		)		(12		)
	Non-U.S.	(171		)		46				(69		)
		(279		)		(3,087		)		(173		)
	Provision for income taxes	$	46,280			$	41,109			$	36,407
	Deferred income taxes represent the tax effects of the temporary differences between book and tax bases and are measured using enacted tax rates that will be in effect when such items are expected to reverse. The Company records a valuation allowance, when necessary, to reduce deferred tax assets to an amount that more likely than not will be realized.
	Significant components of the Company's net deferred income tax asset at December 31, 2014 and 2013 consist of the following (in thousands):
		At December 31,
		2014				2013
	Deferred income tax assets (liabilities):
	Stock-based compensation	$	8,923			$	7,953
	Non-deductible realized loss on investments	5,565				6,706
	Dividend equivalents on unvested restricted stock units	5,204				4,504
	Unrealized loss (gain) on investments	840				(1,296		)
	Other	981				1,687
	Subtotal	21,513				19,554
	Less: valuation allowance	(6,405		)		(5,410		)
	Deferred income tax asset - net	$	15,108			$	14,144
	The Company had capital loss carryforwards of approximately $11,700,000 and $11,300,000 for the years ended December 31, 2014 and December 31, 2013 which, if unused, will expire in years 2015 to 2019. The valuation allowance on the net deferred income tax asset increased approximately $995,000 during the year ended December 31, 2014.
	At December 31, 2014, the Company had approximately $6,346,000 of total gross unrecognized tax benefits. Of this total, approximately $4,076,000 (net of the federal benefit on state issues) represents the amount of unrecognized tax benefits that, if recognized, would favorably affect the Company's effective tax rate in future periods. The Company expects to reduce its unrecognized tax benefits by $430,000 within the next twelve months due to the lapse of the statute of limitations on certain positions.
	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows (in thousands):
		Liability for Unrecognized Tax Benefits
	Gross unrecognized tax benefits balance at January 1, 2012	$	4,712
	Addition for tax positions of current year	933
	Addition for tax positions of prior years	74
	Reduction of tax positions from prior years	(820		)
	Gross unrecognized tax benefits balance at December 31, 2012	$	4,899
	Addition for tax positions of current year	1,421
	Addition for tax positions of prior years	1,597
	Reduction of tax positions from prior years	(1,990		)
	Gross unrecognized tax benefits balance at December 31, 2013	$	5,927
	Addition for tax positions of current year	1,230
	Addition for tax positions of prior years	90
	Reduction of tax positions from prior years	(901		)
	Gross unrecognized tax benefits balance at December 31, 2014	$	6,346
	The Company recognizes potential interest and penalties related to uncertain tax positions in the provision for income taxes. At December 31, 2014 and 2013, the Company had approximately $1,267,000 and $1,170,000, respectively, in potential interest and penalties associated with uncertain tax positions.
	The tax years 2010 through 2014 remain open to examination by various taxing jurisdictions.
	A reconciliation of the Company's statutory federal income tax rate and the effective tax rate for the years ended December 31, 2014, 2013 and 2012 is as follows:
		Years Ended December 31,
		2014			2013			2012
	U.S. statutory tax rate	35	%		35	%		35	%
	State and local income taxes, net of federal income taxes	4.5	%		4.8	%		4.4	%
	Non-deductible loss on investments	0.6	%		—	%		—	%
	Reserve adjustments	—	%		0.6	%		(0.1	)%
	Non-taxable gain on investments	—	%		(0.3	)%		(1.2	)%
	Foreign operations tax differential	(2.2	)%		(2.5	)%		(2.4	)%
	Other	0.1	%		—	%		(0.2	)%
	Effective income tax rate	38	%		37.6	%		35.5	%

Concentration_of_Credit_Risk

Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit Risk
	The Company's cash and cash equivalents are principally on deposit with three major financial institutions. The Company is subject to credit risk should these financial institutions be unable to fulfill their obligations.
	The following affiliated fund and third-party institutional separate account relationship provided 10 percent or more of the total revenue of the Company (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Cohen & Steers Realty Shares, Inc. (CSR):
	Investment advisory and administration fees	$	45,904		$	42,618		$	36,853
	Percent of total revenue	15		%	14		%	13		%
	One Institutional Separate Account Relationship:
	Investment advisory and administration fees	$	37,505		$	36,704		$	40,904
	Portfolio consulting and other	1,970			5,510			12,000
	Total	$	39,475		$	42,214		$	52,904
	Percent of total revenue	13		%	14		%	19		%
	The table below presents revenue by client domicile for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31,
		2014			2013			2012
	United States	$	256,137		$	238,591		$	204,872
	Non - U.S.
	Japan	40,179			42,603			53,356
	Other	17,618			16,519			15,325
	Total	$	313,934		$	297,713		$	273,553

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unadudited)	Selected Quarterly Financial Data (unaudited)
	The table below presents selected quarterly financial data for 2014 and 2013. The data presented should be read in conjunction with the consolidated financial statements of Cohen & Steers, Inc. and “Management's Discussion and Analysis of Financial Condition and Results of Operations” included herein (in thousands, except per share data):
		Quarter
		1st		2nd		3rd		4th		Total
	2014
	Revenue	$	72,835	$	78,412	$	80,845	$	81,842	$	313,934
	Operating income	27,596		29,668		32,327		32,350		121,941
	Net income attributable to common stockholders	19,445		22,183		18,184		15,698		75,510
	Earnings per share attributable to common stockholders:
	Basic	0.44		0.49		0.41		0.35		1.69
	Diluted	0.43		0.49		0.4		0.34		1.65
	Weighted-average shares outstanding:
	Basic	44,633		44,825		44,839		44,852		44,788
	Diluted	45,483		45,530		45,689		45,866		45,643
	2013
	Revenue	$	72,459	$	77,796	$	74,026	$	73,432	$	297,713
	Operating income	20,710		28,557		27,719		29,356		106,342
	Net income attributable to common stockholders	15,141		15,282		18,283		19,413		68,119
	Earnings per share attributable to common stockholders:
	Basic	0.34		0.34		0.41		0.44		1.54
	Diluted	0.34		0.34		0.41		0.43		1.51
	Weighted-average shares outstanding:
	Basic	44,137		44,306		44,317		44,325		44,272
	Diluted	44,882		45,002		45,106		45,338		45,083

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	The Company has evaluated the need for disclosures and/or adjustments resulting from subsequent events through the date the consolidated financial statements were issued. Other than the items described below, the Company determined that there were no additional subsequent events that required disclosure and/or adjustment.
	On February 26, 2015, CNS declared a quarterly dividend on its common stock in the amount of $0.25 per share. This dividend will be payable on March 26, 2015 to stockholders of record at the close of business on March 13, 2015.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Accounting Estimates	Accounting Estimates—The preparation of the consolidated financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosures of contingent assets and liabilities at the dates of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. Management believes the estimates used in preparing the consolidated financial statements are reasonable and prudent. Actual results could differ from those estimates.
Reclassifications	Reclassifications—Certain prior year amounts have been reclassified to conform to the current year presentation.
Consolidation	Consolidation—The Company consolidates operating entities deemed to be voting interest entities if the Company owns a majority of the voting interest. The Company also consolidates any variable interest entities (VIEs) in which the Company is the primary beneficiary. The Company records noncontrolling interests in consolidated subsidiaries for which the Company’s ownership is less than 100 percent. The equity method of accounting is used for investments in affiliates in which the Company’s ownership ranges from 20 to 50 percent, or in instances in which the Company is able to exercise significant influence but not control.
VIE	A VIE is an entity in which either (a) the equity investment at risk is not sufficient to permit the entity to finance its own activities without additional financial support or (b) the group of holders of the equity investment at risk lack certain characteristics of a controlling financial interest. The primary beneficiary is the entity that has the obligation to absorb a majority of the expected losses or the right to receive the majority of the residual returns. Investments and redemptions or amendments to the governing documents of the respective entities could affect an entity's status as a VIE or the determination of the primary beneficiary. The Company assesses whether entities in which it has an interest are VIEs upon initial involvement and at each reporting date. The Company assesses whether it is the primary beneficiary of any VIEs identified by evaluating its economic interests in the entity held either directly by the Company and its affiliates or indirectly through employees.
Cash and Cash Equivalents	Cash and Cash Equivalents—Cash equivalents consist of short-term, highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
Due from Broker	Due from Broker—The Company conducts business, primarily through its consolidated seed investments, with brokers for certain of its investment activities. The clearing and custody operations for these investment activities are performed pursuant to agreements with prime brokers. The due from broker balance represents cash and cash equivalents balances at brokers and net receivables and payables for unsettled security transactions.
Investments	Investments—Management of the Company determines the appropriate classification of its investments at the time of purchase and re-evaluates such determination at each statement of financial condition date.
	Investments classified as trading represent securities held within the affiliated funds that the Company consolidates and are measured at fair value based on quoted market prices, market prices obtained from independent pricing services engaged by management or as determined by the Company’s valuation committee. Unrealized gains and losses are recorded as gain (loss) from trading investments—net in the Company’s consolidated statements of operations.
	Investments classified as equity method investments are accounted for using the equity method, under which the Company recognizes its respective share of the investee’s net income or loss for the period. As of December 31, 2014, the Company's equity method investments consisted of interests in affiliated funds which measure their underlying investments at fair value and report a net asset value on a recurring basis. The carrying amounts of these investments approximate their fair value.
	Investments classified as available-for-sale are comprised of equity securities, investment-grade preferred instruments and investments in Company-sponsored open-end mutual funds. These investments are carried at fair value based on quoted market prices or market prices obtained from independent pricing services engaged by management, with unrealized gains and losses, net of tax, reported in accumulated other comprehensive income. The Company periodically reviews each individual security position that has an unrealized loss, or impairment, to determine if that impairment is other than temporary. If the Company believes an impairment of a security position is other than temporary, the loss will be recognized in the Company’s consolidated statements of operations. An other than temporary impairment is presumed to have occurred if the available-for-sale investment has an unrealized loss continuously for 12 or more months.
	From time to time, the affiliated funds consolidated by the Company enter into derivative contracts to gain exposure to the underlying commodities markets or to hedge market and credit risks of the underlying portfolios utilizing options, total return swaps, credit default swaps and futures contracts. These instruments are measured at fair value with gains and losses recorded as gain (loss) from trading investments—net in the Company's consolidated statements of operations. The fair values of these instruments are recorded in other assets or other liabilities and accrued expenses in the Company's consolidated statements of financial condition. As of December 31, 2014, none of the outstanding derivative contracts were subject to a master netting agreement or other similar arrangement.
	Additionally, from time to time, the Company enters into foreign exchange contracts to hedge its currency exposure related to client receivables. These instruments are measured at fair value with gains and losses recorded in other non-operating income in the Company's consolidated statements of operations. The fair values of these contracts are recorded in other assets or other liabilities and accrued expenses in the Company's consolidated statements of financial condition.
Goodwill and Intangible Assets	Goodwill and Intangible Assets—Goodwill represents the excess of the cost of the Company’s investment in the net assets of an acquired company over the fair value of the underlying identifiable net assets at the date of acquisition. Goodwill and indefinite lived intangible assets are not amortized but are tested at least annually for impairment by comparing the fair value to their carrying amounts. Finite lived intangible assets are amortized over their useful lives and are tested for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interest—Redeemable noncontrolling interest represents third-party interests in the Company's consolidated entities. This interest is redeemable at the option of the investors and therefore is not treated as permanent equity. Redeemable noncontrolling interest is remeasured at redemption value which approximates the fair value at each reporting period.
Investment Advisory and Administration Fees	Investment Advisory and Administration Fees—The Company earns revenue by providing asset management services to institutional accounts and to Company-sponsored open-end mutual funds and closed-end funds. Investment advisory fees are earned pursuant to the terms of underlying advisory contracts, and are based on a contractual fee rate applied to the assets in the portfolio, net of applicable waivers, if any. The Company also earns administration fees from certain Company-sponsored open-end mutual funds and closed-end funds pursuant to the terms of underlying administration contracts. Administration fees are based on the average assets under management of such funds. Investment advisory and administration fees revenue is recognized as such fees are earned.
Distribution and Service Fee Revenue	Distribution and Service Fee Revenue—CSS acts as the principal distributor of the Company’s sponsored open-end mutual funds which may offer the following classes: Class A (initial sales load), Class C (back end sales load), Class R (load retirement) and Class Z (no load retirement). Effective May 2007, the Company suspended sales of Class B shares and all remaining Class B shares are expected to convert to Class A shares in 2015. Distribution and service fee revenue is based on the average daily net assets of the funds as detailed below. Distribution and service fee revenue is earned daily and is recorded gross of any third-party distribution and service fee expense for applicable share classes.
	Pursuant to distribution plans with the Company's sponsored open-end mutual funds, CSS receives distribution fees of 25bps for Class A shares, 75bps for Class C shares and 50bps for Class R shares. CSS also receives shareholder servicing fees of 10bps on Class A shares, 25bps on Class C shares and 15bps on Class Z shares, pursuant to shareholder servicing plans with the funds. Effective October 1, 2014, Class Z shares no longer accrued shareholder servicing fees.
Distribution and Service Fee Expense	Distribution and Service Fee Expense—Distribution and service fee expense includes distribution fees, service fees and intermediary assistance payments. Distribution and service fee expense is recorded as incurred.
	Distribution fee expense represents payments made to qualified dealers/institutions for (i) assistance in connection with the distribution of the Company's sponsored open-end mutual funds' shares and (ii) for other expenses such as advertising costs and printing and distribution of prospectuses to investors. Such amounts may also be used to pay financial intermediaries for services as specified in the terms of written agreements complying with Rule 12b-1 of the Investment Company Act of 1940 (Rule 12b-1). CSS pays distribution fee expense based on the average daily net assets under management of 25bps on Class A shares, 75bps on Class C shares and 50bps on Class R shares.
	Shareholder servicing fee expense represents payments made to qualified dealers/institutions for shareholder account service and maintenance. These services are provided pursuant to written agreements with such qualified institutions. CSS pays service fee expenses based on the average daily net assets under management of 10bps on Class A shares, 25bps on Class C shares and 15bps on Class Z shares. Effective October 1, 2014, Class Z shares no longer paid shareholder service fees.
	Intermediary assistance payments represent payments to qualified dealers/institutions for activities related to distribution, shareholder servicing and marketing and support of Company-sponsored open-end mutual funds and are incremental to those described above. Intermediary assistance payments may be based on the average assets under management, the number of accounts being serviced, or a combination thereof.
Portfolio Consulting and Other	Portfolio Consulting and Other—The Company earns portfolio consulting and other fees by: i) providing portfolio consulting services in connection with model-based strategies accounts; ii) earning a licensing fee for the use of the Company's proprietary indices; and iii) providing portfolio monitoring services related to a number of unit investment trusts. This revenue is earned pursuant to the terms of the underlying contract, and the fee schedules for these relationships vary based on the type of services the Company provides for each relationship. This revenue is recognized as such fees are earned.
Stock-based Compensation	Stock-based Compensation—The Company recognizes compensation expense for the grant-date fair value of awards of equity instruments granted to employees. This expense is recognized over the period during which employees are required to provide service. The Company also estimates forfeitures.
Income Taxes	Income Taxes—The Company records the current and deferred tax consequences of all transactions that have been recognized in the consolidated financial statements in accordance with the provisions of the enacted tax laws. Deferred tax assets are recognized for temporary differences that will result in deductible amounts in future years at tax rates that are expected to apply in those years. Deferred tax liabilities are recognized for temporary differences that will result in taxable income in future years at tax rates that are expected to apply in those years. The Company records a valuation allowance, when necessary, to reduce deferred tax assets to an amount that more likely than not will be realized.
Currency Translation and Transactions	Currency Translation and Transactions—Assets and liabilities of subsidiaries having non-U.S. dollar functional currencies are translated at exchange rates at the applicable consolidated statement of financial condition date. Revenue and expenses are translated at average exchange rates during the period. The gains or losses resulting from translating non-U.S. dollar functional currency into U.S. dollars are included in the Company's consolidated statements of comprehensive income. Gains or losses resulting from non-U.S. dollar currency transactions are included in other non-operating income in the consolidated statements of operations.
Comprehensive Income	Comprehensive Income—The Company reports all changes in comprehensive income in the consolidated statements of comprehensive income. Comprehensive income includes net income or loss attributable to common stockholders, foreign currency translation gain and loss (net of tax), unrealized gain and loss from available-for-sale investments (net of tax) and reclassification to statements of operations of gain and loss from available-for-sale investments (net of tax).
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements—In February 2015, the Financial Accounting Standards Board (FASB) issued new guidance amending the current accounting for consolidation of certain legal entities. These amendments modify the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities, eliminate the presumption that a general partner should consolidate a limited partnership, affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships, and provide a scope exception from consolidation guidance for reporting entities with interests in certain investment funds. This new guidance will be effective for the Company’s first quarter of 2016. The Company is currently evaluating the potential impact on its consolidated financial statements and related disclosures.
	In August 2014, the FASB issued new guidance regarding disclosure of going concern uncertainties in the financial statements. The guidance requires management to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued at each annual and interim reporting period. This new guidance will be effective for the Company’s first quarter of 2017. The Company does not anticipate that the adoption of this new guidance will have a material impact on the Company's consolidated financial statements.
	In May 2014, the FASB issued new guidance which outlined a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The core principle of the revenue model is that an entity recognizes 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 new guidance will be effective for the Company's first quarter of 2017 and requires either a retrospective or a modified retrospective approach to adoption. Early application is prohibited. The Company is currently evaluating the potential impact on its consolidated financial statements and related disclosures, as well as the available transition methods.
	In July 2013, the FASB issued new guidance on the presentation of unrecognized tax benefits when a net operating loss carryforward, a similar tax loss, or a tax credit carryfoward exists. An entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward unless a net operating loss carryforward, a similar tax loss or a tax credit carryforward is not available as of the reporting date or the entity does not intend to use the deferred tax asset for this purpose (provided that the tax law permits a choice). This new guidance was effective for the Company's first quarter of 2014. The adoption of this new guidance did not have a material impact on the Company's consolidated financial statements.
	In June 2013, the FASB issued new guidance which clarifies the characteristics of an investment company and provides guidance for assessing whether an entity is an investment company. From time to time the Company consolidates certain of its affiliated funds which are considered investment companies. The Company retains the specialized investment company accounting for such funds in consolidation. This new guidance was effective for the Company’s first quarter of 2014. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements.
Valuation Techniques	Valuation Techniques
	In certain instances, debt and equity securities are valued on the basis of prices from an orderly transaction between market participants provided by reputable brokers/dealers or pricing services. In determining the value of a particular investment, pricing services may use information with respect to transactions in such investments, broker quotes, pricing matrices, market transactions in comparable investments and various relationships between investments. As part of its independent price verification process, the Company selectively performs detailed reviews of valuations provided by broker/dealers or pricing services.
	Foreign exchange contracts are valued by interpolating a value using the spot foreign exchange rate and forward points (based on the spot rate and currency interest rate differentials), which are all inputs that are observable in active markets (level 2).
	In the absence of observable market prices, the Company values its investments using valuation methodologies applied on a consistent basis. For some investments, little market activity may exist; management's determination of fair value is then based on the best information available in the circumstances, and may incorporate management's own assumptions and involves a significant degree of judgment, taking into consideration a combination of internal and external factors. Such investments are valued on a quarterly basis, taking into consideration any changes in key inputs and changes in economic and other relevant conditions, and valuation models are updated accordingly. The valuation process also includes a review by the Company's valuation committee which is comprised of senior members from various departments within the Company, including investment management. The valuation committee provides independent oversight of the valuation policies and procedures.

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Goodwill and Intangible Assets	The following summarizes the changes in the Company's goodwill and intangible assets during the years ended December 31, 2014 and 2013 (in thousands):
		Goodwill				Finite Lived Intangible				Indefinite Lived
						Assets				Intangible Assets
	Balance at January 1, 2013	$	20,122			$	540			$	1,250
	Currency revaluation	550				—				—
	Amortization during 2013	—				(89		)		—
	Balance at December 31, 2013	$	20,672			$	451			$	1,250
	Currency revaluation	(1,552		)		—				—
	Amortization during 2014	—				(89		)		—
	Balance at December 31, 2014	$	19,120			$	362			$	1,250
Schedule of Intangible Assets	The following is a summary of the intangible assets at December 31, 2014 and December 31, 2013 (in thousands):
		Remaining		Gross				Accumulated				Intangible
		Amortization		Carrying				Amortization				Assets, Net
		Period		Amount
		(in months)
	2014
	Amortized intangible assets:
	Client relationships	48		$	1,543			$	(1,181	)		$	362
	Non-amortized intangible assets:
	Mutual fund management contracts	—		1,250				—				1,250
	Total			$	2,793			$	(1,181	)		$	1,612
	2013
	Amortized intangible assets:
	Client relationships	60		$	1,543			$	(1,092	)		$	451
	Non-amortized intangible assets:
	Mutual fund management contracts	—		1,250				—				1,250
	Total			$	2,793			$	(1,092	)		$	1,701
Schedule Future Amortization Expense	Estimated future amortization expense is as follows (in thousands):
	Periods Ending December 31,	Estimated
		Amortization
		Expense
	2015	$	89
	2016	89
	2017	89
	2018	95
	2019	—
	Total	$	362

Investments_Tables

Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Summary of Investment Holdings	The following is a summary of the Company's investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Trading investments	$	9,509		$	15,668
	Equity method investments	28,550			24,724
	Available-for-sale investments	21,269			10,449
Equity Method Investments	The following is the condensed statement of financial condition for the aggregate of the Company's equity method investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Total assets	$	166,111		$	163,072
	Total liabilities	5,434			757
	Net assets	160,677			162,315
	The following is the condensed statement of operations for the aggregate of the Company's equity method investments for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31, (1)
		2014			2013			2012
	Total revenue	$	2,896		$	1,142		$	1,524
	Total expenses	2,019			1,985			2,618
	Net realized gain (loss) and net change in unrealized appreciation (depreciation) on investments	(14,827		)	12,833			6,188
	Net (loss) income	$	(13,950	)	$	11,990		$	5,094
	_________________________
	(1)    Amounts are included only for the time in which the investees were accounted for under the equity method.
	The following is the condensed statement of financial condition for the aggregate of the Company's equity method investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Total assets	$	166,111		$	163,072
	Total liabilities	5,434			757
	Net assets	160,677			162,315
	The following is the condensed statement of operations for the aggregate of the Company's equity method investments for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31, (1)
		2014			2013			2012
	Total revenue	$	2,896		$	1,142		$	1,524
	Total expenses	2,019			1,985			2,618
	Net realized gain (loss) and net change in unrealized appreciation (depreciation) on investments	(14,827		)	12,833			6,188
	Net (loss) income	$	(13,950	)	$	11,990		$	5,094
	_________________________
	(1)    Amounts are included only for the time in which the investees were accounted for under the equity method.
Summary of Fair Value of Trading Investments and Equity Method Investments	The following is a summary of the fair value of trading investments and equity method investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31, 2014						December 31, 2013
		Trading Investments			Equity Method Investments			Trading Investments			Equity Method Investments
	ACOM	$	—		$	7,612		$	7,300		$	—
	CDF	7,000			—			—			—
	GRP-CIP	2,509			—			2,740			—
	GRP-TE	—			111			—			116
	MLO	—			20,827			5,125			—
	Offshore Fund	—			—			—			412
	Onshore Fund	—			—			503			—
	RAP	—			—			—			24,196
	Total	$	9,509		$	28,550		$	15,668		$	24,724
Gain (Loss) from Trading Investments	Gain (loss) from trading investments—net for the years ended December 31, 2014, 2013 and 2012, which represent realized and unrealized gains and losses recorded by the funds the Company consolidates, are summarized below (in thousands):
		Years Ended December 31,
		2014			2013			2012
	ACOM	$	(505	)	$	(484	)	$	—
	CDF	(2,804		)	—			—
	GLIF	—			—			142
	GRP-CIP	151			356			55
	MLO	1,567			155			—
	Onshore Fund	24			495			2,994
	RAP	—			(7,134		)	891
	Total (loss) gain from trading investments—net	$	(1,567	)	$	(6,612	)	$	4,082
Schedule of Equity in Earnings (Losses) of Affiliates	Equity in earnings (losses) of affiliates for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Years Ended December 31,
		2014			2013			2012
	ACOM	$	(1,228	)	$	—		$	—
	GRP-TE	11			13			—
	MLO	(1,511		)	—			—
	Offshore Fund	20			149			1,050
	RAP	753			678			—
	Total equity in earnings (losses) of affiliates	$	(1,955	)	$	840		$	1,050
Schedule of Available-for-Sale Investments Reconciliation	The following is a summary of the cost, gross unrealized gains, gross unrealized losses and fair value of available-for-sale investments as of December 31, 2014 and December 31, 2013 (in thousands):
		December 31, 2014
		Cost			Gross			Gross			Fair
					Unrealized			Unrealized			Value
					Gains			Losses (1)
	Preferred securities	$	1,043		$	54		$	(2	)	$	1,095
	Common stocks	5,366			627			(155		)	5,838
	Company-sponsored mutual funds	15,010			4			(678		)	14,336
	Total available-for-sale investments	$	21,419		$	685		$	(835	)	$	21,269
	_________________________
	(1)    At December 31, 2014, there were no securities with unrealized losses continuously for a period of more than 12 months.
		December 31, 2013
		Cost			Gross			Gross			Fair
					Unrealized			Unrealized			Value
					Gains			Losses (1)
	Preferred securities	$	4,142		$	183		$	(40	)	$	4,285
	Common stocks	5,400			698			(132		)	5,966
	Company-sponsored mutual funds	197			1			—			198
	Total available-for-sale investments	$	9,739		$	882		$	(172	)	$	10,449
	_________________________
	(1)    At December 31, 2013, there were no securities with unrealized losses continuously for a period of more than 12 months.
Schedule of Realized Gains (Losses) on Available-for-sale investments	Sales proceeds, gross realized gains and losses from available-for-sale investments for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Proceeds from sales	$	12,704		$	26,541		$	25,736
	Gross realized gains	2,251			2,743			1,918
	Gross realized losses	(210		)	(484		)	(681		)

Fair_Value_Tables

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value [Abstract]
Fair Value Measurements, Recurring and Nonrecurring	The following table presents fair value measurements as of December 31, 2013 (in thousands):
		Level 1			Level 2			Level 3				Total
	Cash equivalents (1)	$	61,551		$	—		$	—			$	61,551
	Trading investments
	Common stocks	$	5,125		$	—		$	503			$	5,628
	Fixed income securities	—			7,300			—				7,300
	Limited partnership interests	—			—			2,740				2,740
	Total trading investments	$	5,125		$	7,300		$	3,243			$	15,668
	Equity method investments	$	24,196		$	—		$	528			$	24,724
	Available-for-sale investments
	Preferred securities	$	960		$	—		$	3,325			$	4,285
	Common stocks	5,966			—			—				5,966
	Company-sponsored mutual funds	198			—			—				198
	Total available-for-sale investments	$	7,124		$	—		$	3,325			$	10,449
	Derivatives - assets
	Foreign exchange contracts	$	—		$	398		$	—			$	398
	Commodity contracts	305			—			—				305
	Total derivatives - assets	$	305		$	398		$	—			$	703
	Derivatives - liabilities
	Commodity contracts	$	275		$	—		$	—			$	275
	Total derivatives - liabilities	$	275		$	—		$	—			$	275
	_________________________
	(1) Comprised of investments in actively traded money market funds measured at net asset value.
	The following table presents fair value measurements as of December 31, 2014 (in thousands):
		Level 1			Level 2			Level 3				Total
	Cash equivalents (1)	$	59,281		$	—		$	—			$	59,281
	Trading investments
	Fixed income securities	$	—		$	7,000		$	—			$	7,000
	Limited partnership interests	—			—			2,509				2,509
	Total trading investments	$	—		$	7,000		$	2,509			$	9,509
	Equity method investments	$	20,827		$	7,612		$	111			$	28,550
	Available-for-sale investments
	Preferred securities	$	1,095		$	—		$	—			$	1,095
	Common stocks	5,838			—			—				5,838
	Company-sponsored mutual funds	14,336			—			—				14,336
	Total available-for-sale investments	$	21,269		$	—		$	—			$	21,269
	Derivatives - assets
	Foreign exchange contracts	$	—		$	505		$	—			$	505
	Commodity contracts	234			—			—				234
	Total derivatives - assets	$	234		$	505		$	—			$	739
	Derivatives - liabilities
	Foreign exchange contracts	$	—		$	12		$	—			$	12
	Commodity contracts	754			—			—				754
	Total derivatives - liabilities	$	754		$	12		$	—			$	766
	_________________________
	(1) Comprised of investments in actively traded money market funds measured at net asset value.
Fair Value, Valuation Technique, Unobservable Inputs	The following table summarizes the changes in level 3 investments measured at fair value on a recurring basis for the years ended December 31, 2014 and 2013 (in thousands):
		Trading						Equity Method Investments				Available-for-sale investments
		Investments
		Common Stocks			Limited Partnership Interests			GRP-TE/Offshore Fund				Preferred Securities
	Balance at January 1, 2013	$	1,168		$	2,142		$	89			$	3,080
	Purchases / contributions	—			393			15				—
	Sales / distributions	(419		)	(151		)	(7,066		)		—
	Realized (losses) gains	(211		)	11			—				—
	Unrealized (losses) gains (1)	(35		)	345			54				245
	Transfers into level 3	—			—			7,436			(2)	—
	Balance at December 31, 2013	$	503		$	2,740		$	528			$	3,325
	Purchases / contributions	—			625			18				—
	Sales / distributions	(527		)	(721		)	(457		)		(4,000		)
	Realized gains	24			64			—				675
	Unrealized (losses) gains (1)	—			(199		)	22				—
	Transfers into (out of) level 3	—			—			—				—
	Balance at December 31, 2014	$	—		$	2,509		$	111			$	—
	_________________________
	-1	Pertains to unrealized gains (losses) from securities held at December 31, 2014 and 2013, respectively.
	-2	Transferred from level 2 to level 3 during the year ended December 31, 2013 due to the imposition of redemption restrictions on the Company's investment in connection with the winding down of the operations of the Offshore Fund.
	The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2013 were:
		Fair Value			Fair Value		Significant	Input /
		(in thousands)			Methodology		Unobservable Inputs	Range
	Common shares of privately-held company	$	503		Market comparable companies		Price / tangible book ratio	1.48x
							Liquidity discount	33%
	Limited partnership interests - direct investments in real estate	$	2,101		Discounted cash flows		Discount rate	9% - 15%
							Exit capitalization rates	8.5% - 9%
							Market rental rates	$15.00 - 16.25 psf
	The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2014 were:
		Fair Value			Fair Value		Significant	Input /
		(in thousands)			Methodology		Unobservable Inputs	Range
	Limited partnership interests - direct investments in real estate	$	1,465		Discounted cash flows		Discount rate	9% - 15%
							Exit capitalization rates	8% - 8.5%
							Market rental rates	$15.00 - 17.00 psf

Derivatives_Tables

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2014
Derivatives [Abstract]
Schedule of Derivative Instruments
		31-Dec-13
		Assets						Liabilities
		Notional			Fair Value			Notional			Fair Value
	Total foreign exchange contracts	$	10,853		$	398		$	—		$	—
	Total commodity contracts	8,115			305			5,738			275
	Total derivatives	$	18,968		$	703		$	5,738		$	275
	The notional amount represents the absolute value amount of all outstanding derivative contracts as of December 31, 2014 and December 31, 2013 (in thousands):
		31-Dec-14
		Assets						Liabilities
		Notional			Fair Value			Notional			Fair Value
	Total foreign exchange contracts	$	11,349		$	505		$	222		$	12
	Total commodity contracts	6,095			234			8,977			754
	Total derivatives	$	17,444		$	739		$	9,199		$	766
Gains (Losses) on Derivatives	Gains and losses from derivative financial instruments for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Equity contracts	$	—		$	(584	)	$	125
	Foreign exchange contracts	95			(218		)	686
	Commodity contracts	(3,280		)	(3,689		)	(517		)
	Credit contracts	—			(21		)	(38		)
	Total derivatives	$	(3,185	)	$	(4,512	)	$	256

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	The following is a summary of property and equipment as of December 31, 2014 and 2013 (in thousands):
		December 31,
		2014			2013
	Equipment	$	6,536		$	8,606
	Furniture and fixtures	2,024			3,487
	Software	15,479			13,405
	Leasehold improvements	9,358			11,374
	Subtotal	33,397			36,872
	Less: Accumulated depreciation and amortization	(22,208		)	(27,048		)
	Property and equipment, net	$	11,189		$	9,824

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following is a reconciliation of the income and share data used in the basic and diluted earnings per share computations for the years ended December 31, 2014, 2013 and 2012 (in thousands, except per share data):
		Years Ended December 31,
		2014			2013		2012
	Net income	$	75,734		$	63,255	$	67,896
	Less: Net (income) loss attributable to redeemable noncontrolling interest	(224		)	4,864		(1,779		)
	Net income attributable to common stockholders	$	75,510		$	68,119	$	66,117
	Basic weighted average shares outstanding	44,788			44,272		43,766
	Dilutive potential shares from restricted stock units	855			811		716
	Diluted weighted average shares outstanding	45,643			45,083		44,482
	Basic earnings per share attributable to common stockholders	$	1.69		$	1.54	$	1.51
	Diluted earnings per share attributable to common stockholders	$	1.65		$	1.51	$	1.49

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table sets forth activity relating to the Company's incentive bonus plans, including Company match and dividend equivalents (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	1,132		$	25.88
	Granted	692		33.38
	Delivered	(464	)	24.72
	Forfeited	(46	)	30.88
	Balance at December 31, 2012	1,314		30.07
	Granted	587		33.55
	Delivered	(400	)	27.79
	Forfeited	(70	)	32.13
	Balance at December 31, 2013	1,431		32.03
	Granted	522		36.67
	Delivered	(472	)	30.84
	Forfeited	(27	)	34.29
	Balance at December 31, 2014	1,454		34.04
	The following table sets forth activity relating to the Company's granted awards of vested RSUs under the SIP for awards to the independent directors and certain employees (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	45		$	19.9
	Granted	10		31.77
	Delivered	(21	)	13.79
	Balance at December 31, 2012	34		27.46
	Granted	9		33.83
	Delivered	(14	)	22.79
	Balance at December 31, 2013	29		31.47
	Granted	9		39.67
	Delivered	(10	)	29.12
	Balance at December 31, 2014	28		34.93
	The following table sets forth activity relating to the Company's granted awards under the above mentioned plans (share data in thousands):
		Number of Shares		Weighted Average
				Grant Date Fair Value
	Balance at January 1, 2012	1,279		$	22.21
	Granted	100		32.34
	Delivered	(346	)	23.57
	Forfeited	(54	)	20.75
	Balance at December 31, 2012	979		22.85
	Granted	305		34.2
	Delivered	(307	)	21.95
	Forfeited	(27	)	25.28
	Balance at December 31, 2013	950		26.72
	Granted	110		37.33
	Delivered	(361	)	24.45
	Forfeited	(9	)	25.69
	Balance at December 31, 2014	690		29.62

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The following table sets forth the amount of revenue the Company earned from these affiliated funds for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31,
		2014			2013		2012
	Investment advisory and administration fees	$	210,316		$	190,058	$	155,931
	Distribution and service fees	14,667			14,359		11,334
		$	224,983		$	204,417	$	167,265
	Sales proceeds, gross realized gains, gross realized losses and dividend income from available-for-sale investments in Company-sponsored mutual funds for the years ended December 31, 2014, 2013 and 2012 are summarized below (in thousands):
		Years Ended December 31,
		2014			2013		2012
	Proceeds from sales	$	192		$	10,715	$	103
	Gross realized gains	—			615		4
	Gross realized losses	(3		)	—		—
	Dividend income	390			9		3

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The Company also leases certain computer and office equipment under noncancelable operating leases expiring at various dates through December 2019. The aggregate minimum future payments under the leases are as follows (in thousands):
	Years Ended December 31,	Operating Leases
	2015	$	11,354
	2016	11,025
	2017	10,213
	2018	9,838
	2019	10,580
	Thereafter	42,859
		$	95,869

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Income before Taxes	The income before provision for income taxes and provision for income taxes for the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Years Ended December 31,
		2014				2013				2012
	Income before provision for income taxes - U.S.	$	108,452			89,963				89,828
	Income before provision for income taxes - Non-U.S.	13,562				14,401				14,475
	Total income before provision for income taxes	$	122,014			$	104,364			$	104,303
	Current taxes:
	U.S. federal	$	38,711			$	36,490			$	29,723
	State and local	4,966				5,025				3,754
	Non-U.S.	2,882				2,681				3,103
		46,559				44,196				36,580
	Deferred taxes:
	U.S. federal	(96		)		(2,754		)		(92		)
	State and local	(12		)		(379		)		(12		)
	Non-U.S.	(171		)		46				(69		)
		(279		)		(3,087		)		(173		)
	Provision for income taxes	$	46,280			$	41,109			$	36,407
Components of Deferred Tax Assets and Liabilities	Significant components of the Company's net deferred income tax asset at December 31, 2014 and 2013 consist of the following (in thousands):
		At December 31,
		2014				2013
	Deferred income tax assets (liabilities):
	Stock-based compensation	$	8,923			$	7,953
	Non-deductible realized loss on investments	5,565				6,706
	Dividend equivalents on unvested restricted stock units	5,204				4,504
	Unrealized loss (gain) on investments	840				(1,296		)
	Other	981				1,687
	Subtotal	21,513				19,554
	Less: valuation allowance	(6,405		)		(5,410		)
	Deferred income tax asset - net	$	15,108			$	14,144
Reconciliation of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows (in thousands):
		Liability for Unrecognized Tax Benefits
	Gross unrecognized tax benefits balance at January 1, 2012	$	4,712
	Addition for tax positions of current year	933
	Addition for tax positions of prior years	74
	Reduction of tax positions from prior years	(820		)
	Gross unrecognized tax benefits balance at December 31, 2012	$	4,899
	Addition for tax positions of current year	1,421
	Addition for tax positions of prior years	1,597
	Reduction of tax positions from prior years	(1,990		)
	Gross unrecognized tax benefits balance at December 31, 2013	$	5,927
	Addition for tax positions of current year	1,230
	Addition for tax positions of prior years	90
	Reduction of tax positions from prior years	(901		)
	Gross unrecognized tax benefits balance at December 31, 2014	$	6,346
Reconciliation of Federal Statutory Income Tax Rate to Effective Rate	A reconciliation of the Company's statutory federal income tax rate and the effective tax rate for the years ended December 31, 2014, 2013 and 2012 is as follows:
		Years Ended December 31,
		2014			2013			2012
	U.S. statutory tax rate	35	%		35	%		35	%
	State and local income taxes, net of federal income taxes	4.5	%		4.8	%		4.4	%
	Non-deductible loss on investments	0.6	%		—	%		—	%
	Reserve adjustments	—	%		0.6	%		(0.1	)%
	Non-taxable gain on investments	—	%		(0.3	)%		(1.2	)%
	Foreign operations tax differential	(2.2	)%		(2.5	)%		(2.4	)%
	Other	0.1	%		—	%		(0.2	)%
	Effective income tax rate	38	%		37.6	%		35.5	%

Concentration_of_Credit_Risk_T

Concentration of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	The table below presents revenue by client domicile for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years Ended December 31,
		2014			2013			2012
	United States	$	256,137		$	238,591		$	204,872
	Non - U.S.
	Japan	40,179			42,603			53,356
	Other	17,618			16,519			15,325
	Total	$	313,934		$	297,713		$	273,553
	The following affiliated fund and third-party institutional separate account relationship provided 10 percent or more of the total revenue of the Company (in thousands):
		Years Ended December 31,
		2014			2013			2012
	Cohen & Steers Realty Shares, Inc. (CSR):
	Investment advisory and administration fees	$	45,904		$	42,618		$	36,853
	Percent of total revenue	15		%	14		%	13		%
	One Institutional Separate Account Relationship:
	Investment advisory and administration fees	$	37,505		$	36,704		$	40,904
	Portfolio consulting and other	1,970			5,510			12,000
	Total	$	39,475		$	42,214		$	52,904
	Percent of total revenue	13		%	14		%	19		%

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The data presented should be read in conjunction with the consolidated financial statements of Cohen & Steers, Inc. and “Management's Discussion and Analysis of Financial Condition and Results of Operations” included herein (in thousands, except per share data):
		Quarter
		1st		2nd		3rd		4th		Total
	2014
	Revenue	$	72,835	$	78,412	$	80,845	$	81,842	$	313,934
	Operating income	27,596		29,668		32,327		32,350		121,941
	Net income attributable to common stockholders	19,445		22,183		18,184		15,698		75,510
	Earnings per share attributable to common stockholders:
	Basic	0.44		0.49		0.41		0.35		1.69
	Diluted	0.43		0.49		0.4		0.34		1.65
	Weighted-average shares outstanding:
	Basic	44,633		44,825		44,839		44,852		44,788
	Diluted	45,483		45,530		45,689		45,866		45,643
	2013
	Revenue	$	72,459	$	77,796	$	74,026	$	73,432	$	297,713
	Operating income	20,710		28,557		27,719		29,356		106,342
	Net income attributable to common stockholders	15,141		15,282		18,283		19,413		68,119
	Earnings per share attributable to common stockholders:
	Basic	0.34		0.34		0.41		0.44		1.54
	Diluted	0.34		0.34		0.41		0.43		1.51
	Weighted-average shares outstanding:
	Basic	44,137		44,306		44,317		44,325		44,272
	Diluted	44,882		45,002		45,106		45,338		45,083

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Consolidation (Details)	Dec. 31, 2014
Minimum
Schedule of Equity Method Investments [Line Items]
Ownership range	20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Ownership range	50.00%

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Non-GAAP Expenses - Distribution and Service Fees (Details) (USD $)	12 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2013	Sep. 30, 2012
	mutual_funds
Schedule of distribution and service fees - Non-GAAP [Line Items]
Number of closed-end mutual funds	2
Distribution Rights [Member]
Schedule of distribution and service fees - Non-GAAP [Line Items]
Distribution and service fees		$7.20	$14.40

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Cumulative Translation Adjustments Balance (Details) (Accumulated Translation Adjustment, USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accumulated Translation Adjustment
Cumulative Translation Adjustments balance [Line Items]
Cumulative Foreign Currency Translation Adjustment, Net of Tax	($1,446)	$2,264	$985

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Goodwill and Intangible Assets (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill
Beginning balance	$20,672	$20,122
Currency revaluation	-1,552	550
Ending balance	19,120	20,672	20,122
Finite Lived Intangible Assets
Finite lived intangible assets, gross			-540
Amortization	-89	-89	-89
Finite Lived Intangible Assets	362	451
Indefinite Lived Intangible Assets
Mutual fund management contracts	$1,250	$1,250	$1,250

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Intangible Assets (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization Period Remaining	48 Months	60 Months
Client relationships, Gross Carrying Amount			$540
Client relationships, Accumulated Amortization	1,181	1,092
Client relationships, Net	362	451
Mutual fund management contracts	1,250	1,250	1,250
Gross Carrying Amount	2,793	2,793
Intangible assets—net	1,612	1,701
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Client relationships, Gross Carrying Amount	1,543	1,543
Client relationships, Accumulated Amortization	1,181	1,092
Client relationships, Net	362	451
Fund Management Contracts Member
Finite-Lived Intangible Assets [Line Items]
Mutual fund management contracts	$1,250	$1,250

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Estimated Future Amortization Expense (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense related to intangible assets	$89	$89	$89
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2015	89
2016	89
2017	89
2018	95
2019	0
Total	$362	$451

Investments_Trading_Equity_Met

Investments - Trading, Equity Method Investments and Available-for-Sale Investments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Trading Investments and Other Trading Assets [Abstract]
Trading investments	$9,509	[1]	$15,668	[1]
Equity Method Investments	28,550		24,724
Gain (loss) from trading investments - net	-1,567		-6,612		4,082
Equity in earnings (losses) of affiliates	-1,955		840		1,050
Available-for-sale investments [Abstract]
Cost	21,419		9,739
Gross Unrealized Gains	685		882
Gross Unrealized Losses	-835	[2]	-172	[3]
Fair Value	21,269		10,449
Available-for-sale investments in an unrealized loss position	15,875		1,785
Proceeds from investing activities [Abstract]
Proceeds from sales	12,704		26,541		25,736
Gross realized gains	2,251		2,743		1,918
Gross realized losses	-210		-484		-681
ACOM
Equity Method Investment, Summarized Financial Information [Abstract]
Total assets	166,111		163,072
Total liabilities	5,434		757
Net assets	160,677		162,315
Total revenue	2,896	[4]	1,142	[4]	1,524	[4]
Total expenses	2,019	[4]	1,985	[4]	2,618	[4]
Net realized gain (loss) and net change in unrealized appreciation (depreciation) on investments	-14,827	[4]	12,833	[4]	6,188	[4]
Net (loss) income	-13,950	[4]	11,990	[4]	5,094	[4]
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		7,300
Equity Method Investments	7,612		0
Gain (loss) from trading investments - net	-505		-484		0
Equity in earnings (losses) of affiliates	-1,228		0		0
CDF
Trading Investments and Other Trading Assets [Abstract]
Trading investments	7,000		0
Equity Method Investments	0		0
Gain (loss) from trading investments - net	-2,804		0		0
CLIF
Trading Investments and Other Trading Assets [Abstract]
Gain (loss) from trading investments - net	0		0		142
GRP-CIP
Trading Investments and Other Trading Assets [Abstract]
Trading investments	2,509		2,740
Equity Method Investments	0		0
Gain (loss) from trading investments - net	151		356		55
GRP-TE
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		0
Equity Method Investments	111		116
Equity in earnings (losses) of affiliates	11		13		0
Onshore Fund
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		503
Equity Method Investments	0		0
Gain (loss) from trading investments - net	24		495		2,994
Offshore Fund
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		0
Equity Method Investments	0		412
Equity in earnings (losses) of affiliates	20		149		1,050
RAP
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		0
Equity Method Investments	0		24,196
Gain (loss) from trading investments - net	0		-7,134		891
Equity in earnings (losses) of affiliates	753		678		0
MLO
Trading Investments and Other Trading Assets [Abstract]
Trading investments	0		5,125
Equity Method Investments	20,827		0
Gain (loss) from trading investments - net	1,567		155		0
Equity in earnings (losses) of affiliates	-1,511		0		0
Preferred securities
Available-for-sale investments [Abstract]
Cost	1,043		4,142
Gross Unrealized Gains	54		183
Gross Unrealized Losses	-2	[2]	-40	[3]
Fair Value	1,095		4,285
Common stock
Available-for-sale investments [Abstract]
Cost	5,366		5,400
Gross Unrealized Gains	627		698
Gross Unrealized Losses	-155	[2]	-132	[3]
Fair Value	5,838		5,966
Company-sponsored mutual funds
Available-for-sale investments [Abstract]
Cost	15,010		197
Gross Unrealized Gains	4		1
Gross Unrealized Losses	-678	[2]	0	[3]
Fair Value	$14,336		$198
[1]	eld as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. (CDF) as of December 31, 2014 and $7,300 attributable to Cohen & Steers Active Commodities Fund, LP (ACOM) as of December 31, 2013.
[2]	At December 31, 2014, there were no securities with unrealized losses continuously for a period of more than 12 months.
[3]	At December 31, 2013, there were no securities with unrealized losses continuously for a period of more than 12 months.
[4]	Amounts are included only for the time in which the investees were accounted for under the equity method.

Fair_Value_Details

Fair Value (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	9,509	[1]	15,668	[1]
Equity method investments	28,550		24,724
Available-for-sale investments	21,269		10,449
Level 3 | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 Ratio Ranges			1.48
Fair Value Inputs, Liquidity Discount			33.36%
Fair Value Inputs, Discount Rate	9.00%		9.00%
Fair Value Inputs, Exit Capitalization	8.00%		8.50%
Fair Value Inputs, Price Per Square Foot	15		15
Level 3 | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 Ratio Ranges
Fair Value Inputs, Discount Rate	15.00%		15.00%
Fair Value Inputs, Exit Capitalization	8.50%		9.00%
Fair Value Inputs, Price Per Square Foot	17		16.25
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	59,281	[2]	61,551	[2]
Trading investments	9,509		15,668
Equity method investments	28,550		24,724
Available-for-sale investments	21,269		10,449
Derivative - assets	739		703
Derivative - liabilities	766		275
Fair Value, Measurements, Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	505		398
Derivative - liabilities	12
Fair Value, Measurements, Recurring | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	234		305
Derivative - liabilities	754		275
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	59,281	[2]	61,551	[2]
Trading investments	0		5,125
Equity method investments	20,827		24,196
Available-for-sale investments	21,269		7,124
Derivative - assets	234		305
Derivative - liabilities	754		275
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	0		0
Derivative - liabilities	0
Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	234		305
Derivative - liabilities	754		275
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	0	[2]	0	[2]
Trading investments	7,000		7,300
Equity method investments	7,612		0
Available-for-sale investments	0		0
Derivative - assets	505		398
Derivative - liabilities	12		0
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	505		398
Derivative - liabilities	12
Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	0		0
Derivative - liabilities	0		0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	0	[2]	0	[2]
Trading investments	2,509		3,243
Equity method investments	111		528
Available-for-sale investments	0		3,325
Derivative - assets	0		0
Derivative - liabilities	0		0
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	0		0
Derivative - liabilities	0
Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets	0		0
Derivative - liabilities	0		0
Preferred securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	1,095		4,285
Preferred securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	1,095		4,285
Preferred securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	1,095		960
Preferred securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	0		0
Preferred securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	0		3,325
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	3,325		3,080
Purchases / contributions	0		0
Sales / distributions	-4,000		0
Realized gains (losses)	675		0
Unrealized gains (losses)	0	[3]	245	[3]
Transfers into (out of) level 3	0		0
Ending Balance	0		3,325
Common stock
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	5,838		5,966
Common stock | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 Fair Value			503
Common stock | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount			0
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments			5,628
Available-for-sale investments	5,838		5,966
Common stock | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments			5,125
Available-for-sale investments	5,838		5,966
Common stock | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	0		0
Common stock | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments			503
Available-for-sale investments	0		0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	503		1,168
Purchases / contributions	0		0
Sales / distributions	-527		-419
Realized gains (losses)	24		-211
Unrealized gains (losses)	0	[3]	-35	[3]
Transfers into (out of) level 3	0		0
Ending Balance	0		503
Fixed income | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	7,000		7,300
Fixed income | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	0		0
Fixed income | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	7,000		7,300
Fixed income | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	0		0
Limited partnership interests | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 Fair Value	1,465		2,101
Limited partnership interests | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	2,509		2,740
Limited partnership interests | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	0		0
Limited partnership interests | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	0		0
Limited partnership interests | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	2,509		2,740
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	2,740		2,142
Purchases / contributions	625		393
Sales / distributions	-721		-151
Realized gains (losses)	64		11
Unrealized gains (losses)	-199	[3]	345	[3]
Transfers into (out of) level 3	0		0
Ending Balance	2,509		2,740
Company-sponsored mutual funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	14,336		198
Company-sponsored mutual funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	14,336		198
Company-sponsored mutual funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	14,336		198
Company-sponsored mutual funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	0		0
Company-sponsored mutual funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments	0		0
GRP-TE/Offshore Funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	0		0
Equity method investments	111		116
GRP-TE/Offshore Funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	528		89
Purchases / contributions	18		15
Sales / distributions	-457		-7,066
Realized gains (losses)	0		0
Unrealized gains (losses)	22	[3]	54	[3]
Transfers into (out of) level 3	0		7,436	[4]
Ending Balance	111		528
[1]	eld as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. (CDF) as of December 31, 2014 and $7,300 attributable to Cohen & Steers Active Commodities Fund, LP (ACOM) as of December 31, 2013.
[2]	Comprised of investments in actively traded money market funds measured at net asset value.
[3]	Pertains to unrealized gains (losses) from securities held at December 31, 2014 and 2013, respectively.
[4]	Transferred from level 2 to level 3 during the year ended December 31, 2013 due to the imposition of redemption restrictions on the Company's investment in connection with the winding down of the operations of the Offshore Fund.

Derivatives_Details

Derivatives (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	($3,185)	($4,512)	$256
Derivative Assets, Notional Amount	17,444	18,968
Derivative Assets, Fair Value	739	703
Derivative Liabilities, Notional Amount	9,199	5,738
Derivative Liabilities, Fair Value	766	275
Securities owned
Derivative [Line Items]
Securities owned and held as collateral		7,300
Due From Broker
Derivative [Line Items]
Cash Collateral for Borrowed Securities	422	2,110
Securities owned
Derivative [Line Items]
Securities owned and held as collateral	650
Equity contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	-584	125
Foreign exchange contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	95	-218	686
Derivative Assets, Notional Amount	11,349	10,853
Derivative Assets, Fair Value	505	398
Derivative Liabilities, Notional Amount	222	0
Derivative Liabilities, Fair Value	12	0
Commodity contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	-3,280	-3,689	-517
Derivative Assets, Notional Amount	6,095	8,115
Derivative Assets, Fair Value	234	305
Derivative Liabilities, Notional Amount	8,977	5,738
Derivative Liabilities, Fair Value	754	275
Credit contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$0	($21)	($38)

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property and Equipment [Line Items]
Depreciation and amortization	$4,535	$5,517	$5,473
Property and equipment, gross	33,397	36,872
Accumulated depreciation and amortization	-22,208	-27,048
Property and equipment, net	11,189	9,824
Minimum
Property and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum
Property and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Equipment
Property and Equipment [Line Items]
Property and equipment, gross	6,536	8,606
Furniture and Fixtures
Property and Equipment [Line Items]
Property and equipment, gross	2,024	3,487
Software
Property and Equipment [Line Items]
Property and equipment, gross	15,479	13,405
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	$9,358	$11,374

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 [Abstract]
Anti-dilutive common stock equivalents excluded from computation (in shares)									0	0
Net income									$75,734	$63,255	$67,896
Less: Net (income) loss attributable to redeemable noncontrolling interest									-224	4,864	-1,779
Net income attributable to common stockholders	$15,698	$18,184	$22,183	$19,445	$19,413	$18,283	$15,282	$15,141	$75,510	$68,119	$66,117
Basic weighted average shares outstanding (in shares)	44,852,000	44,839,000	44,825,000	44,633,000	44,325,000	44,317,000	44,306,000	44,137,000	44,788,000	44,272,000	43,766,000
Dilutive potential shares from restricted stock units (in shares)									855,000	811,000	716,000
Diluted weighted average shares outstanding (in shares)	45,866,000	45,689,000	45,530,000	45,483,000	45,338,000	45,106,000	45,002,000	44,882,000	45,643,000	45,083,000	44,482,000
Basic earnings per share attributable to common stockholders (in dollars per share)	$0.35	$0.41	$0.49	$0.44	$0.44	$0.41	$0.34	$0.34	$1.69	$1.54	$1.51
Diluted earnings per share attributable to common stockholders (in dollars per share)	$0.34	$0.40	$0.49	$0.43	$0.43	$0.41	$0.34	$0.34	$1.65	$1.51	$1.49

StockBased_Compensation_Vested

Stock-Based Compensation - Vested RSUs (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Common stock, shares issued	48,593,812	47,735,793
Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$34,343
Stock Incentive Plan | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Authorized	16,000,000
Stock Incentive Plan | Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued	12,700,000
Allocated Share-based Compensation Expense	8,590	8,491	7,328
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested, Number of Shares [Roll Forward] [Roll Forward]
Balance at Beginning of Period (shares)	29,000	34,000	45,000
Granted (shares)	9,000	9,000	10,000
Delivered (shares)	-10,000	-14,000	-21,000
Balance at End of Period (shares)	28,000	29,000	34,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested, Weighted Average Grant Date Fair Value [Abstract] [Abstract]
Balance at beginning of period, Weighted Average Grant Date Fair Value (usd per share)	$31.47	$27.46	$19.90
Granted, Weighted Average Grant Date Fair Value (usd per share)	$39.67	$33.83	$31.77
Delivered, Weighted Average Grant Date Fair Value (usd per share)	$29.12	$22.79	$13.79
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	$34.93	$31.47	$27.46
Stock Incentive Plan | Vested Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$352	$300	$326
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested, Number of Shares [Roll Forward] [Roll Forward]
Balance at End of Period (shares)	28,000

StockBased_Compensation_Unvest

Stock-Based Compensation - Unvested RSUs and Incentive Bonus Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Common stock, shares issued	48,593,812	47,735,793
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans, Weighted Average Grant Date Fair Value [Roll Forward]
Employee stock purchase plans	14,000	13,000	16,000
Vesting period of unvested employee stock compensation, number of years	3 years
Common stock | Incentive Bonus Plans for Employees
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans, Weighted Average Grant Date Fair Value [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Annual Aggregate Purchases Per Employee	25,000
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee	600,000
Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Allocated Share-based Compensation Expense	34,343,000
Restricted Stock Units (RSUs) | Common stock | Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance at beginning of period (shares)	950,000	979,000	1,279,000
Granted (shares)	110,000	305,000	100,000
Delivered (shares)	-361,000	-307,000	-346,000
Forfeited (shares)	-9,000	-27,000	-54,000
Balance at end of period (shares)	690,000	950,000	979,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Balance at beginning of period, Weighted Average Grant Date Fair Value (usd per share)	26.72	22.85	22.21
Granted, Weighted Average Grant Date Fair Value (usd per share)	37.33	34.2	32.34
Delivered, Weighted Average Grant Date Fair Value (usd per share)	24.45	21.95	23.57
Forfeited, Weighted Average Grant Date Fair Value (usd per share)	25.69	25.28	20.75
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	29.62	26.72	22.85
Common stock, shares issued	12,700,000
Allocated Share-based Compensation Expense	8,590,000	8,491,000	7,328,000
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans, Weighted Average Grant Date Fair Value [Roll Forward]
Delivered, Weighted Average Grant Date Fair Value (usd per share)	24.45	21.95	23.57
Restricted Stock Units (RSUs) | Common stock | Incentive Bonus Plans for Employees
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Delivered, Weighted Average Grant Date Fair Value (usd per share)	30.84	27.79	24.72
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans [Roll Forward]
Balance at beginning of period (shares)	1,431,000	1,314,000	1,132,000
Granted (shares)	522,000	587,000	692,000
Delivered (shares)	472,000	400,000	-464,000
Forfeited (shares)	-27,000	-70,000	-46,000
Balance at end of period (shares)	1,454,000	1,431,000	1,314,000
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans, Weighted Average Grant Date Fair Value [Roll Forward]
Balance at beginning of period, Weighted Average Grant Date Fair Value (usd per share)	32.03	30.07	25.88
Granted, Weighted Average Grant Date Fair Value (usd per share)	36.67	33.55	33.38
Delivered, Weighted Average Grant Date Fair Value (usd per share)	30.84	27.79	24.72
Forfeited, Weighted Average Grant Date Fair Value (usd per share)	34.29	32.13	30.88
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	34.04	32.03	30.07
Discount from market price, purchase date	15.00%
Restricted Stock Units (RSUs) | Common stock | Mandatory Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Common stock, shares issued	1,412,000
Allocated Share-based Compensation Expense	16,178,000	12,863,000	10,069,000
Restricted Stock Units (RSUs) | Common stock | Voluntary Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Common stock, shares issued	42,000
Restricted Stock Units (RSUs) | Common stock | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Allocated Share-based Compensation Expense	87,000	72,000	76,000
Vested Restricted Stock Units (RSUs) | Common stock | Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Allocated Share-based Compensation Expense	352,000	300,000	326,000
Vested Restricted Stock Units (RSUs) | Common stock | Voluntary Plan
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Allocated Share-based Compensation Expense	116,000	113,000	577,000

401k_and_ProfitSharing_Plan_De

401(k) and Profit-Sharing Plan (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer Matching Contribution, Percent of Match	50.00%
The Plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Maximum Employee Subscription Rate	100.00%
Forfeitures during period	$83	$176	$72
Employer matching contributions	1,074	1,462	1,110
Common stock | Restricted Stock Units (RSUs)
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Allocated Share-based Compensation Expense	$34,343

Related_Party_Transactions_Det

Related Party Transactions (Details) (Affiliated Entity, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions Revenue [Abstract]
Investment advisory and administrative fees	$210,316	$190,058	$155,931
Distribution and service fees	14,667	14,359	11,334
Total	224,983	204,417	167,265
Related Party Transactions Summary [Abstract]
Proceeds from sales	192	10,715	103
Gross realized gains	0	615	4
Gross realized losses	-3	0	0
Dividend income	390	9	3
Advisory fees waived			299
Fund expenses, included in general and administrative expenses	9,218	9,332	6,345
Receivables, company sponsored mutual funds	$19,750	$18,026
Maximum
Related Party Transactions Summary [Abstract]
Investment advisory agreement term	10 years

Regulatory_Requirements_Detail

Regulatory Requirements (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Securities Registered Domestically
Financial Instruments Owned and Pledged as Collateral
Net Capital	$1,440
Excess Capital	1,281
Foreign Country
Financial Instruments Owned and Pledged as Collateral
Net Capital	58,806
Excess Capital	$56,611

Commitments_and_Contingencies_1

Commitments and Contingencies - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Commitments
Loss Contingencies [Line Items]
Long-term Purchase Commitments, Time Period	12 years
Commitment to invest
Loss Contingencies [Line Items]
Other Commitment	5,100,000
Long-term committment, funded amount	3,200,000

Commitments_and_Contingencies_2

Commitments and Contingencies - Other Obligations (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Aggregate Minimum Future Payments [Line Items]
Lessee Leasing Arrangements, Operating Leases, Term of Contract	10 years
Sublease rental income	$70	$876	$1,025
Rent expense	10,103	10,067	8,535
Rent Obligations
Aggregate Minimum Future Payments [Line Items]
2015	11,354
2016	11,025
2017	10,213
2018	9,838
2019	10,580
Thereafter	42,859
Other Commitment	$95,869

Income_Taxes_Narrative_Details

Income Taxes - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Effective tax rate	38.00%	37.60%	35.50%
Effective tax rate, excluding discrete items		38.00%	36.00%
Unrecognized deferred tax in investments of foreign subsidiaries	$73,425
Gross unrecognized tax benefits	6,346	5,927	4,899	4,712
Unrecognized tax benefits that impact effective tax rate in future periods	4,076
Reduction in unrecognized tax benefits due to lapse of applicable statute of limitations	430
Uncertain tax positions, accrued interest and penalties	$1,267	$1,170

Income_Taxes_Schedule_of_Incom

Income Taxes - Schedule of Income before Taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income before provision for income taxes
U.S. income before provision for income taxes	$108,452	$89,963	$89,828
Foreign income before provision for income taxes	13,562	14,401	14,475
Income before provision for income taxes	122,014	104,364	104,303
Current taxes:
U.S. federal	38,711	36,490	29,723
State and local	4,966	5,025	3,754
Non-U.S.	2,882	2,681	3,103
Total	46,559	44,196	36,580
Deferred taxes:
U.S. federal	-96	-2,754	-92
State and local	-12	-379	-12
Non-U.S.	-171	46	-69
Deferred income taxes	-279	-3,087	-173
Provision for income taxes	$46,280	$41,109	$36,407

Income_Taxes_Components_of_Def

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Stock-based compensation	$8,923	$7,953
Non-deductible realized loss on investments	5,565	6,706
Dividend equivalents on unvested restricted stock units	5,204	4,504
Unrealized gains on investments	840	-1,296
Other	981	1,687
Subtotal	21,513	19,554
Less: valuation allowance	-6,405	-5,410
Deferred income tax asset - net	15,108	14,144
Capital Loss Carryforward	11,700	11,300
Changes in Valuation Allowance	($995)

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Gross unrecognized tax benefits balance	$5,927	$4,899	$4,712
Addition for tax positions of current year	1,230	1,421	933
Addition for tax positions of prior years	90	1,597	74
Reduction of tax positions from prior years	-901	-1,990	-820
Gross unrecognized tax benefits balance	$6,346	$5,927	$4,899

Income_Taxes_Reconciliation_of1

Income Taxes - Reconciliation of Federal Statutory Income Tax Rate to Effective Rate (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of federal income taxes	4.50%	4.80%	4.40%
Non-deductible loss on investments	0.60%	0.00%	0.00%
Reserve adjustments	0.00%	0.60%	-0.10%
Non-taxable gain on investments	0.00%	-0.30%	-1.20%
Foreign operations tax differential	-2.20%	-2.50%	-2.40%
Other	0.10%	0.00%	-0.20%
Effective income tax rate	38.00%	37.60%	35.50%

Concentration_of_Credit_Risk_D

Concentration of Credit Risk (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, 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
									financial_institution
Concentration Risk (Line Items)
Revenues	$81,842	$80,845	$78,412	$72,835	$73,432	$74,026	$77,796	$72,459	$313,934	$297,713	$273,553
Number of financial institutions									3
Sales Revenue, Segment | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									313,934	297,713	273,553
Sales Revenue, Segment | United States | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									256,137	238,591	204,872
Sales Revenue, Segment | Japan | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									40,179	42,603	53,356
Sales Revenue, Segment | Other | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									17,618	16,519	15,325
Cohen & Steers Realty Shares, Inc. | Sales Revenue, Services | Customer Concentration Risk
Concentration Risk (Line Items)
Percent of total revenue									15.00%	14.00%	13.00%
Cohen & Steers Realty Shares, Inc. | Sales Revenue, Services | Investment advisory and administration fees | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									45,904	42,618	36,853
One Institutional Separate Account Relationship | Sales Revenue, Services | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									39,475	42,214	52,904
Percent of total revenue									13.00%	14.00%	19.00%
One Institutional Separate Account Relationship | Sales Revenue, Services | Investment advisory and administration fees | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									37,505	36,704	40,904
One Institutional Separate Account Relationship | Sales Revenue, Services | Portfolio consulting and other revenue | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$1,970	$5,510	$12,000

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per 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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$81,842	$80,845	$78,412	$72,835	$73,432	$74,026	$77,796	$72,459	$313,934	$297,713	$273,553
Operating income	32,350	32,327	29,668	27,596	29,356	27,719	28,557	20,710	121,941	106,342	96,432
Net income attributable to common stockholders	$15,698	$18,184	$22,183	$19,445	$19,413	$18,283	$15,282	$15,141	$75,510	$68,119	$66,117
Earnings per share attributable to common stockholders:
Basic (in dollars per share)	$0.35	$0.41	$0.49	$0.44	$0.44	$0.41	$0.34	$0.34	$1.69	$1.54	$1.51
Diluted (in dollars per share)	$0.34	$0.40	$0.49	$0.43	$0.43	$0.41	$0.34	$0.34	$1.65	$1.51	$1.49
Weighted-average shares outstanding:
Basic (shares)	44,852	44,839	44,825	44,633	44,325	44,317	44,306	44,137	44,788	44,272	43,766
Diluted (shares)	45,866	45,689	45,530	45,483	45,338	45,106	45,002	44,882	45,643	45,083	44,482

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 26, 2015
Subsequent Event [Line Items]
Dividends declared per share	$1.88	$1.80	$2.22
Dividend Declared | Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share				$0.25