Cohen & Steers (CNS) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 20, 2018	Jun. 30, 2017
Entity Information
Entity Registrant Name	COHEN & STEERS INC
Entity Central Index Key	1,284,812
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		46,738,105
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 878

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents		$ 193,452	$ 183,234
Trading investments ($414 and $487), ($68,101 and $6,987)	[1],[2]	74,856	12,689
Equity method investments		6,176	6,459
Available-for-sale investments		27,074	35,396
Accounts receivable		53,854	46,288
Due from broker ($5,410 and $475)	[1]	6,429	1,579
Property and equipment—net		15,040	15,964
Goodwill and intangible assets—net		20,379	19,118
Deferred income tax asset—net		5,812	5,619
Other assets ($931 and $43)	[1]	7,053	7,382
Total assets		410,125	333,728
Liabilities:
Accrued compensation		41,370	35,333
Distribution and service fees payable		6,231	6,452
Income tax payable		19,892	9,375
Due to broker ($3,203 and $0)	[1]	3,282	0
Deferred rent		5,994	6,229
Other liabilities and accrued expenses ($291 and $75)	[1]	10,025	9,672
Total liabilities		86,794	67,061
Commitments and contingencies
Redeemable noncontrolling interest		47,795	853
Stockholders’ equity:
Common stock, $0.01 par value; 500,000,000 shares authorized; 51,104,593 and 50,415,152 shares issued at December 31, 2017 and 2016, respectively		511	504
Additional paid-in capital		570,486	543,829
Accumulated deficit		(137,972)	(127,957)
Accumulated other comprehensive income, net of tax		(3,671)	(5,885)
Less: Treasury stock, at cost, 4,789,608 and 4,524,694 shares at December 31, 2017 and 2016, respectively		(153,818)	(144,677)
Total stockholders’ equity		275,536	265,814
Total liabilities and stockholders’ equity		$ 410,125	$ 333,728
[1]	Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2017 and 2016 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund, Cohen & Steers Co-Investment Partnership, L.P. and Cohen & Steers SICAV Global Preferred Securities Fund, which were variable interest entities as of December 31, 2017 and 2016, respectively.
[2]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.

Consolidated Statements of Fin3

Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Common stock, par value		$ 0.01	$ 0.01
Common stock, shares authorized		500,000,000	500,000,000
Common stock, shares issued		51,104,593	50,415,152
Common stock, shares outstanding		46,314,985	45,890,458
Treasury stock, shares		4,789,608	4,524,694
Trading investments	[1],[2]	$ 74,856	$ 12,689
Due from broker	[1]	6,429	1,579
Other assets	[1]	7,053	7,382
Due to broker	[1]	3,282	0
Other liabilities and accrued expenses	[1]	10,025	9,672
Trading investments
Trading investment and held as collateral		414	487	[2]
GLI SICAV, GRP-CIP and SICAV Preferred
Trading investments		68,101
Due from broker		5,410
Other assets		931
Due to broker		3,203
Other liabilities and accrued expenses		$ 291
GLI SICAV & GRP-CIP [Member]
Trading investments			6,987
Due from broker			475
Other assets			43
Due to broker			0
Other liabilities and accrued expenses			$ 75
[1]	Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2017 and 2016 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund, Cohen & Steers Co-Investment Partnership, L.P. and Cohen & Steers SICAV Global Preferred Securities Fund, which were variable interest entities as of December 31, 2017 and 2016, respectively.
[2]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Investment advisory and administration fees		$ 346,832	$ 319,667	$ 303,729
Distribution and service fees		20,156	19,396	16,001
Portfolio consulting and other		11,206	10,813	8,925
Total revenue		378,194	349,876	328,655
Expenses:
Employee compensation and benefits		124,076	115,607	107,710
Distribution and service fees		39,632	39,590	36,330
General and administrative		52,623	51,558	50,853
Depreciation and amortization		7,117	7,610	6,213
Total expenses		223,448	214,365	201,106
Operating income		154,746	135,511	127,549
Non-operating income (loss):
Interest and dividend income		4,333	2,119	1,600
Gain (loss) from trading investments—net	[1]	1,915	218	(2,376)
Equity in earnings (losses) of affiliates—net		(242)	3,324	(10,378)
Gain (loss) from available-for-sale investments—net		347	1,451	(2,648)
Other gains (losses)—net		(699)	780	(1,003)
Total non-operating income (loss)		5,654	7,892	(14,805)
Income before provision for income taxes		160,400	143,403	112,744
Provision for income taxes		67,914	50,593	48,407
Net income		92,486	92,810	64,337
Less: Net (income) loss attributable to redeemable noncontrolling interest		(547)	126	214
Net income attributable to common stockholders		$ 91,939	$ 92,936	$ 64,551
Earnings per share attributable to common stockholders:
Basic (in dollars per share)		$ 1.98	$ 2.02	$ 1.42
Diluted (in dollars per share)		$ 1.96	$ 2	$ 1.41
Weighted average shares outstanding:
Basic (shares)		46,353	45,951	45,433
Diluted (shares)		46,979	46,432	45,897
[1]	Includes net income (loss) attributable to redeemable noncontrolling interest for the periods presented.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 92,486	$ 92,810	$ 64,337
Less: Net (income) loss attributable to redeemable noncontrolling interest	(547)	126	214
Net income attributable to common stockholders	91,939	92,936	64,551
Other comprehensive income (loss), net of tax:
Foreign currency translation income (loss)	2,064	(2,937)	(2,462)
Net unrealized gain (loss) from available-for-sale investments	497	2,346	(2,447)
Reclassification to statements of operations of realized (gain) loss from available-for-sale investments	(347)	(1,451)	2,648
Other comprehensive income (loss)	2,214	(2,042)	(2,261)
Total comprehensive income attributable to common stockholders	$ 94,153	$ 90,894	$ 62,290

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity and Redeemable Noncontrolling Interest - USD ($) $ in Thousands	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
Beginning balance at Dec. 31, 2014		$ 486	$ 489,266	$ (142,786)	$ (1,582)	$ (117,403)	$ 227,981
Beginning balance (redeemable noncontrolling interest) at Dec. 31, 2014								$ 607
Beginning balance (shares of common stock, net) at Dec. 31, 2014		44,793,000
Dividends		$ 0	0	(69,861)	0	0	(69,861)
Issuance of common stock		$ 11	623	0	0	0	634	0
Issuance of common stock, shares		1,097,000
Repurchase of common stock		$ 0	0	0	0	(19,234)	(19,234)	0
Repurchase of common stock, shares		(450,000)
Tax benefits associated with restricted stock units—net		$ 0	5,262	0	0	0	5,262	0
Issuance of restricted stock units		0	2,109	0	0	0	2,109	0
Amortization of restricted stock units—net		0	22,566	0	0	0	22,566	0
Forfeitures of vested restricted stock units		0	29	0	0	0	29	0
Net income (loss)	$ 64,337	0	0	64,551	0	0	64,551	(214)
Other comprehensive income (loss)	(2,261)	0	0	0	(2,261)	0	(2,261)	0
Distributions to redeemable noncontrolling interest		0	0	0	0	0	0	(10)
Contributions from redeemable noncontrolling interest	10,951	0	0	0	0	0	0	10,951
Ending balance at Dec. 31, 2015		$ 497	519,855	(148,096)	(3,843)	(136,637)	231,776
Ending balance (shares of common stock, net) at Dec. 31, 2015		45,440,000
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2015								11,334
Dividends		$ 0	0	(72,797)	0	0	(72,797)
Issuance of common stock		$ 7	749	0	0	0	756	0
Issuance of common stock, shares		724,000
Repurchase of common stock		$ 0	0	0	0	(8,040)	(8,040)	0
Repurchase of common stock, shares		(274,000)
Tax benefits associated with restricted stock units—net		$ 0	(758)	0	0	0	(758)	0
Issuance of restricted stock units		0	2,457	0	0	0	2,457	0
Amortization of restricted stock units—net		0	21,555	0	0	0	21,555	0
Forfeitures of vested restricted stock units		0	(29)	0	0	0	(29)	0
Net income (loss)	92,810	0	0	92,936	0	0	92,936	(126)
Other comprehensive income (loss)	(2,042)	0	0	0	(2,042)	0	(2,042)	0
Distributions to redeemable noncontrolling interest		0	0	0	0	0	0	(342)
Contributions from redeemable noncontrolling interest	4,023	0	0	0	0	0	0	4,023
Transfer of redeemable noncontrolling interest in consolidated entity		0	0	0	0	0		(14,036)
Ending balance at Dec. 31, 2016	$ 265,814	$ 504	543,829	(127,957)	(5,885)	(144,677)	265,814
Ending balance (shares of common stock, net) at Dec. 31, 2016	45,890,458	45,890,000
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2016								853
Dividends		$ 0	0	(101,669)	0	0	(101,669)
Issuance of common stock		$ 7	741	0	0	0	748	0
Issuance of common stock, shares		690,000
Repurchase of common stock		$ 0	0	0	0	(9,141)	(9,141)	0
Repurchase of common stock, shares		(265,000)
Issuance of restricted stock units		$ 0	3,974	0	0	0	3,974	0
Amortization of restricted stock units—net		0	22,042	(285)	0	0	21,757	0
Forfeitures of vested restricted stock units		0	(100)	0	0	0	(100)	0
Net income (loss)	$ 92,486	0	0	91,939	0	0	91,939	547
Other comprehensive income (loss)	2,214	0	0	0	2,214	0	2,214	0
Distributions to redeemable noncontrolling interest		0	0	0	0	0	0	(263)
Contributions from redeemable noncontrolling interest	46,658	0	0	0	0	0	0	46,658
Ending balance at Dec. 31, 2017	$ 275,536	$ 511	$ 570,486	$ (137,972)	$ (3,671)	$ (153,818)	$ 275,536
Ending balance (shares of common stock, net) at Dec. 31, 2017	46,314,985	46,315,000
Ending balance (redeemable noncontrolling interest) at Dec. 31, 2017								$ 47,795

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity and Redeemable Noncontrolling Interest (parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends declared per share	$ 2.12	$ 1.54	$ 1.50

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income		$ 92,486	$ 92,810	$ 64,337
Adjustments to reconcile net income to net cash provided by operating activities:
Stock compensation expense		21,769	21,649	22,686
Depreciation and amortization		7,117	7,610	6,213
Deferred rent		(235)	(139)	640
(Gain) loss from trading investments—net	[1]	(1,915)	(218)	2,376
Equity in (earnings) losses of affiliates—net		242	(3,324)	10,378
(Gain) loss from available-for-sale investments—net		(347)	(1,451)	2,648
Deferred income taxes		(314)	(900)	7,392
Foreign currency (gain) loss		47	1,684	(443)
Changes in operating assets and liabilities:
Accounts receivable		(7,613)	(3,413)	(724)
Due from brokers		(4,850)	(1,261)	(4,299)
Deferred commissions		(1,894)	(3,909)	(2,572)
Trading investments		(60,252)	(3,956)	(30,036)
Other assets		(576)	(1,442)	(1,266)
Accrued compensation		6,064	4,855	2,228
Distribution and service fees payable		(221)	260	(803)
Due to broker		3,282	1,771	4,364
Income tax payable		10,517	2,110	5,231
Other liabilities and accrued expenses		946	2,222	1,446
Net cash provided by (used in) operating activities		64,253	114,958	89,796
Cash flows from investing activities:
Proceeds from redemptions of equity method investments		41	363	1,184
Purchases of available-for-sale investments		(16,901)	(8,096)	(5,663)
Proceeds from sales of available-for-sale investments		25,811	20,814	7,303
Purchases of property and equipment		(3,242)	(10,183)	(2,427)
Net cash provided by (used in) investing activities		5,709	2,898	397
Cash flows from financing activities:
Excess tax benefits associated with restricted stock units		0	0	4,822
Issuance of common stock		636	642	539
Repurchase of common stock		(9,141)	(8,040)	(19,234)
Dividends to stockholders		(98,313)	(70,825)	(68,177)
Distributions to redeemable noncontrolling interest		(263)	(342)	(10)
Contributions from redeemable noncontrolling interest		46,658	4,023	10,951
Net cash provided by (used in) financing activities		(60,423)	(74,542)	(71,109)
Net increase (decrease) in cash and cash equivalents		9,539	43,314	19,084
Effect of foreign exchange rate changes on cash and cash equivalents		679	(2,808)	(1,294)
Cash and cash equivalents, beginning of the year		183,234	142,728	124,938
Cash and cash equivalents, end of the year		$ 193,452	$ 183,234	$ 142,728
[1]	Includes net income (loss) attributable to redeemable noncontrolling interest for the periods presented.

Consolidated Statements of Cas9

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income taxes paid, net	$ (57,726)	$ (49,331)	$ (30,885)
Fully vested restricted stock units issued	618	486	425
Restricted stock unit dividend equivalents, net of forfeitures	$ 3,356	1,972	$ 1,684
LPX
Transfer of redeemable noncontrolling interest in consolidated entity		14,036
Non-cash increase in equity method investments		14,550
Non-cash reclassification from Equity method investment to Available-for-sale investment		15,045
MLO
Non-cash reclassification from Equity method investment to Available-for-sale investment		$ 12,995

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2017
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 (CSAL), Cohen & Steers UK Limited (CSUK) and Cohen & Steers Japan, LLC (collectively, the Company). The Company is a global investment manager specializing in liquid real assets, including real estate securities, listed infrastructure, commodities and natural resource equities, as well as preferred securities and other income solutions. Founded in 1986, the Company is headquartered in New York City, with offices in London, Hong Kong, Tokyo and Seattle. 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 Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Recently Adopted Accounting Pronouncements —In March 2016, the Financial Accounting Standards Board (FASB) issued new guidance amending the current accounting for an investment that becomes qualified for the equity method of accounting. The guidance requires that the cost of acquiring an additional interest in the investment, if any, that resulted in it qualifying for the equity method be added to the carrying value of the investment. The equity method will then be applied from that point forward without any retroactive application or adjustment. This new guidance was effective for the Company’s first quarter of 2017. The adoption of this new guidance did not have a material impact on its consolidated financial statements and related disclosures. In March 2016, the FASB issued new guidance which simplifies several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, excess tax benefits, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company adopted this guidance on January 1, 2017. As a result, the Company reclassified $285,000 from additional paid-in capital to retained earnings on January 1, 2017. Prospectively beginning January 1, 2017, excess tax benefits or tax deficiencies are now reflected in the consolidated statements of operations as a component of the provision for income taxes. For the year ended December 31, 2017, the Company recognized $49,000 of excess tax benefits. Additionally, the consolidated statements of cash flows now reflect excess tax benefits from share-based payments as an operating activity, rather than a financing activity. Finally, the Company elected to account for forfeitures as they occur, rather than estimate expected forfeitures. 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. Consolidation of Company-sponsored Funds —Investments in Company-sponsored funds and management fees are evaluated at inception and thereafter, if there is a reconsideration event, in order to determine whether to apply the Variable Interest Entity (VIE) model or the Voting Interest Entity (VOE) model. In performing this analysis, all of the Company’s management fees are presumed to be commensurate and at market and are therefore not considered variable interests. 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 (a) the power to direct the activities of the VIE that most significantly affect its performance and (b) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE. 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 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. VIEs for which the Company is deemed to be the primary beneficiary are consolidated. Investments in Company-sponsored funds that are determined to be VOEs are consolidated when the Company’s ownership interest is greater than 50% of the outstanding voting interests of the fund or when the Company is the general partner of the fund and the limited partners do not have substantive kick-out or participating rights in the fund. The Company records noncontrolling interests in consolidated funds for which the Company’s ownership is less than 100% . See Note 4 for further discussion about the Company’s seed investments. Cash and Cash Equivalents —Cash and cash equivalents are on deposit with three major financial institutions and consist of short-term, highly liquid investments, which are readily convertible into cash and have original maturities of three months or less. Due from/to Brokers —The Company conducts business, primarily with respect to 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 contractual agreements. The due from/to brokers balance represents cash and cash equivalents balances at brokers/custodians and/or receivables and payables for unsettled securities 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 management and approved 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 represent seed investments in which the Company owns between 20 - 50% of the outstanding voting interests in the affiliated fund or when it is determined that the Company is able to exercise significant influence but not control over the investments. When using the equity method, the Company recognizes its respective share of the affiliated investee fund net income or loss for the period which is recorded as equity in earnings (losses) of affiliates—net in the Company’s consolidated statements of operations. As of December 31, 2017 , the Company’s equity method investments consisted of interests in affiliated funds measured at fair value based on quoted market prices or NAV (or its equivalent) as a practical expedient 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, fixed income securities, investment-grade preferred instruments and investments in Company-sponsored open-end funds where the Company has neither control nor the ability to exercise significant influence. 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, based on available quantitative and qualitative information as of the report date, the loss will be recognized as gain (loss) from available-for-sale investments—net in the Company’s consolidated statements of operations. 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 based on their settlement price at the close of trading on the associated commodities exchange or board of trade 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 on the Company’s consolidated statements of financial condition. As of December 31, 2017 , 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 certain client receivables. These instruments are measured at fair value with gains and losses recorded in other non-operating income (loss) 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 on 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 funds. This interest is redeemable at the option of the investors and therefore is not treated as permanent equity. Redeemable noncontrolling interest is recorded 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 and closed-end funds. Investment advisory fees are earned pursuant to the terms of investment management agreements and are based on a contractual fee rate applied to the assets in the portfolio. The Company also earns administration fees from certain Company-sponsored open-end 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 fee revenue is recognized when earned. Distribution and Service Fee Revenue —Distribution and service fee revenue is based on the average daily net assets of certain share classes of the Company’s sponsored open-end funds distributed by CSS. Distribution and service fee revenue is earned daily and is generally recorded gross of any third-party distribution and service fee expense for applicable share classes. Distribution and Service Fee Expense —Distribution and service fee expense includes distribution fees, shareholder servicing fees and intermediary assistance payments. Distribution and service fee expense is recorded on an accrual basis. Distribution fee expense represents payments made to qualified intermediaries for (i) assistance in connection with the distribution of the Company’s sponsored open-end 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). The Company pays distribution fee expense based on the average daily net assets under management of certain share classes of certain of the funds. Shareholder servicing fee expense represents payments made to qualified intermediaries for shareholder account service and maintenance. These services are provided pursuant to written agreements with such qualified institutions. The Company pays shareholder serving fee expense generally based on the average assets under management or the number of accounts being serviced. Intermediary assistance payments represent payments to qualified intermediaries for activities related to distribution, shareholder servicing and marketing and support of Company-sponsored open-end funds and are incremental to those described above. Intermediary assistance payments are generally based on the average assets under management or the number of accounts being serviced. Portfolio Consulting and Other —The Company earns portfolio consulting and other fees by (i) providing portfolio consulting services in connection with model-based strategy accounts, (ii) earning a licensing fee for the use of the Company’s proprietary indexes 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 when earned. Stock-based Compensation —The Company recognizes compensation expense for the grant-date fair value of awards of equity instruments to employees. This expense is recognized over the period during which employees are required to provide service. Forfeitures are recorded as incurred. 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. The calculation of tax liabilities involves dealing with uncertainties in the application of complex tax laws and regulations in a multitude of jurisdictions across the Company’s global operations. A tax benefit from an uncertain tax position may be recognized when it is more likely than not that the position will be sustained upon examination, including resolution of any related appeals or litigation processes, on the basis of the technical merits. The Company records potential interest and penalties related to uncertain tax positions in the provision for income taxes in the consolidated statements of operations. 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 of such subsidiaries 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. The cumulative translation adjustment was $(4,781,000) , $(6,845,000) and $(3,908,000) as of December 31, 2017 , 2016 and 2015, respectively. Gains or losses resulting from non-U.S. dollar currency transactions are included in other non-operating income (loss) in the consolidated statements of operations. 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, as well as the net of tax amounts attributable to foreign currency translation gain (loss), unrealized gain (loss) from available-for-sale investments and the reclassification of realized gain (loss) from available-for-sale investments to the statements of operations. Recently Issued Accounting Pronouncements —In February 2018, the FASB issued new guidance allowing entities to reclassify certain tax effects related to the enactment of the Tax Act from accumulated other comprehensive income (AOCI) to retained earnings. Prior to the issuance of the new guidance, a portion of the previously recognized deferred tax effects recorded in AOCI was “left stranded” in AOCI as the effect of remeasuring the deferred taxes using the reduced federal corporate income tax rate was required to be recorded through income. The new guidance allows these stranded tax effects to be reclassified from AOCI to retained earnings. The new guidance will be effective on January 1, 2019, with early adoption permitted and is to be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is still assessing which adoption method it will choose but it does not expect either method to have a material effect on its consolidated financial statements and related disclosures. In August 2017, the FASB issued new guidance amending the accounting for hedging activities. The new guidance (i) expands hedge accounting for nonfinancial and financial risk components and amends measurement methodologies to more closely align hedge accounting with an entity’s risk management activities, (ii) decreases the complexity of preparing and understanding hedge results through eliminating the separate measurement and reporting of hedge ineffectiveness, (iii) enhances transparency, comparability and understandability of hedge results through enhanced disclosures and changing the presentation of hedge results to align the effects of the hedging instrument and the hedged item and (iv) reduces the cost and complexity of applying hedge accounting by simplifying the manner in which assessments of hedge effectiveness may be performed. The new guidance will be effective on January 1, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this new guidance on its consolidated financial statements and related disclosures. In May 2017, the FASB issued new guidance for modification accounting related to share-based payment transactions in order to provide clarity and to reduce current diversity in practice. This new guidance does not fundamentally change the notion of a modification. Instead, the amendments clarify which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments became effective on January 1, 2018 and must be applied prospectively to any awards modified on or after the adoption date. The adoption of the new guidance did not have a material effect on the Company’s consolidated financial statements and related disclosures. In January 2017, the FASB issued guidance to simplify the goodwill impairment test by removing the requirement to perform a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. This new guidance will be effective on January 1, 2020. The Company does not expect the adoption of the new guidance to have a material effect on its consolidated financial statements and related disclosures. In August 2016, the FASB amended the current guidance on the classification of certain cash receipts and payments in the statement of cash flows. This guidance is intended to unify the currently diverse presentations and classifications, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. The Company evaluated the eight issues and concluded that only distributions received from equity method investees is applicable to the Company. This amended guidance became effective on January 1, 2018 and was adopted retrospectively. The Company made an accounting policy election to use the Cumulative Earnings Approach when determining whether distributions received from equity method investments should be classified as either operating or investing activities within the Company’s consolidated statements of cash flows. In February 2016, the FASB issued guidance introducing a new lease model which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. The new guidance establishes a right-of-use model (ROU) that requires a lessee to recognize an ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The new guidance also requires disclosures by lessees and lessors to enable users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The new guidance is effective on January 1, 2019, with early adoption permitted. The Company expects to adopt the new guidance on its effective date. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Company is continuing to assess the effect of adoption, it currently believes the most significant change relates to the recognition of new ROU assets and lease liabilities on its consolidated statements of financial condition for its office space and other operating leases. The Company does not expect a significant change in its leasing activity between now and adoption. The Company is still assessing which of the available practical expedients it plans to elect upon adoption. In January 2016, the FASB issued new guidance amending the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. Upon adoption of this guidance, changes in the fair value of the Company’s available-for-sale equity investments will be reported through earnings rather than through other comprehensive income. This new guidance became effective on January 1, 2018 and required a cumulative-effect adjustment to beginning retained earnings in the amount of approximately $1,323,000 , net of tax. Additionally, if the Company had applied the new guidance for the year ended December 31, 2017, approximately $250,000 of net unrealized gains recorded in other comprehensive income would have been recorded in non-operating income (loss) in the Company’s consolidated statement of operations. 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. In March 2016, the FASB issued a revision which clarifies (a) determination of the appropriate unit of account under the revenue standard’s principal versus agent guidance and (b) application of the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. In April 2016, the FASB issued an amendment to provide more detailed guidance and examples related to (a) identifying performance obligations and (b) licenses of intellectual property. In May 2016, the FASB amended the standard to clarify the guidance on assessing collectibility, presenting sales taxes, measuring noncash consideration, and certain transition matters. This new guidance became effective for the Company’s first quarter of 2018 and was adopted retrospectively. The adoption of the new standard did not have a material impact on the timing of recognition for the majority of the Company’s revenue but will affect the presentation of certain costs on either a gross or net basis. In addition, the adoption of the new standard will require additional disclosures in 2018.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following table summarizes the changes in the Company’s goodwill and intangible assets during the years ended December 31, 2017 and 2016 (in thousands): Goodwill Finite-Lived Intangible Assets Indefinite-Lived Intangible Assets Balance at January 1, 2016 $ 17,975 $ 273 $ 1,250 Currency revaluation (291 ) — — Amortization N/A (89 ) N/A Balance at December 31, 2016 $ 17,684 $ 184 $ 1,250 Currency revaluation 1,350 — — Amortization N/A (89 ) N/A Balance at December 31, 2017 $ 19,034 $ 95 $ 1,250 The following table summarizes the Company’s intangible assets at December 31, 2017 and 2016 (in thousands): Remaining Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Intangible Assets, Net 2017 Amortized intangible assets: Client relationships 12 $ 1,543 $ (1,448 ) $ 95 Non-amortized intangible assets: Mutual fund management contracts — 1,250 — 1,250 Total $ 2,793 $ (1,448 ) $ 1,345 2016 Amortized intangible assets: Client relationships 24 $ 1,543 $ (1,359 ) $ 184 Non-amortized intangible assets: Mutual fund management contracts — 1,250 — 1,250 Total $ 2,793 $ (1,359 ) $ 1,434 Amortization expense related to the intangible assets was approximately $89,000 for each of the years ended December 31, 2017, 2016 and 2015 , respectively. The remaining future amortization expense is summarized in the table below (in thousands): Period Ending December 31, Remaining Amortization Expense 2018 $ 95

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Investments [Abstract]
Investment Holdings	Investments The following table summarizes the Company’s investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Trading investments $ 74,856 $ 12,689 Equity method investments 6,176 6,459 Available-for-sale investments 27,074 35,396 Gain (loss) from seed investments for the years ended December 31, 2017, 2016 and 2015 is summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Gain (loss) from trading investments—net (1) $ 1,915 $ 218 $ (2,376 ) Equity in earnings (losses) of affiliates—net (242 ) 3,324 (10,378 ) Gain (loss) from available-for-sale investments—net 347 1,451 (2,648 ) Number of new funds seeded 2 — 2 _________________________ (1) Includes net income (loss) attributable to redeemable noncontrolling interest for the periods presented. Voting Interest Entities The Cohen & Steers Funds ICAV (ICAV), an Irish alternative investment fund (AIF), and the Cohen & Steers Active Commodities Fund (Commodities Sub-Fund), a sub-fund within the ICAV, were launched by the Company in January 2017, and meet the definition of an investment company. The Company is the investment adviser of the Commodities Sub-Fund for which it receives a management fee. The ICAV and the Commodities Sub-Fund are each a VOE and the Company’s ownership interest in the ICAV is less than 20%; therefore, the Company classifies its investment in the Commodities Sub-Fund as an available-for-sale investment. The Cohen & Steers Low Duration Preferred and Income Fund, Inc. (LPX), launched by the Company in December 2015, is an open-end fund for which the Company is the investment adviser. LPX is a VOE and the Company owned the majority of the outstanding voting interests through February 29, 2016. Accordingly, the underlying assets and liabilities and results of operations of LPX 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 March 1, 2016, the Company no longer owned the majority of the outstanding voting interest in LPX; however, it was determined that the Company had significant influence over the financial decisions of LPX and therefore classified its investment in LPX using the equity method of accounting. Effective October 1, 2016, the Company’s ownership interest in LPX fell below 20% and the Company no longer had significant influence over LPX. Accordingly, the Company began classifying its investment in LPX as an available-for-sale investment until the second quarter of 2017, when the Company sold its remaining interest in LPX. The Cohen & Steers Active Commodities Strategy Fund, Inc. (CDF), launched by the Company in May 2014, is an open-end fund for which the Company is the investment adviser. CDF is a VOE and the Company owned the majority of the outstanding voting interests in the fund as of December 31, 2017 . 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 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 limited partners of ACOM, 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 a VOE. 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. As of December 31, 2017 , the Company’s ownership in ACOM was approximately 12% ; however, as the general partner, the Company has significant influence over the financial decisions of ACOM and therefore classifies its investment in ACOM using the equity method of accounting. The Cohen & Steers MLP & Energy Opportunity Fund, Inc. (MLO), launched by the Company in December 2013, is an open-end fund for which the Company is the investment adviser. MLO is a VOE. Effective November 1, 2014, as a result of its ownership interest, it was determined that the Company had significant influence over the financial decisions of MLO and therefore classified its investment in MLO using the equity method of accounting. Effective June 1, 2016, the Company’s ownership interest in MLO fell below 20% and the Company no longer had significant influence over MLO. Accordingly, the Company began classifying its investment in MLO as an available-for-sale investment. Cohen & Steers Real Assets Fund, Inc. (RAP), launched by the Company in January 2012, is an open-end fund for which the Company is the investment adviser. RAP is a VOE. The Company classified its investment in RAP as an available-for-sale investment until the fourth quarter of 2016 when the Company sold its remaining interest in RAP. Variable Interest Entities The Cohen & Steers SICAV Global Preferred Securities Fund (SICAV Preferred), a Luxembourg-domiciled undertaking for collective investments in transferable securities (UCITS), was launched by the Company in May 2017 and meets the definition of an investment company. The Company is the investment adviser of SICAV Preferred for which it receives a management fee. SICAV Preferred is a VIE and the Company is the primary beneficiary. As of December 31, 2017 , the Company’s ownership interest in SICAV Preferred was approximately 26% . Accordingly, the underlying assets and liabilities and results of operations of SICAV Preferred have been included in the Company’s consolidated financial statements with the third-party interests classified as redeemable noncontrolling interest. The Cohen & Steers SICAV Global Listed Infrastructure Fund (GLI SICAV), a Luxembourg-domiciled UCITS, was launched by the Company in September 2015 and meets the definition of an investment company. The Company is the investment adviser of GLI SICAV for which it receives a management fee. GLI SICAV is a VIE and the Company is the primary beneficiary. As of December 31, 2017 , the Company was the only investor in the fund and therefore, the Company would absorb all of the expected losses and residual returns of GLI SICAV. Accordingly, the underlying assets and liabilities and results of operations of GLI SICAV have been included in the Company’s consolidated financial statements. 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. 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. As of December 31, 2017 , the Company’s ownership in GRP-TE was approximately 0.2% ; however, as the general partner, the Company has significant influence over the financial decisions of GRP-TE and therefore classifies its investment using the equity method of accounting. 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 11 for further discussion regarding the Company’s co-investment commitment. GRP-CIP is a VIE and the Company is the primary beneficiary as it owns 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. The following table represents the portion of the consolidated statements of financial condition attributable to the consolidated VIEs as of December 31, 2017 and 2016. The assets may only be used to settle obligations of each VIE and the liabilities are the sole obligation of each VIE, for which creditors do not have recourse to the general credit of the Company (in thousands): December 31, 2017 December 31, 2016 GLI SICAV GRP-CIP SICAV Preferred Total GLI SICAV GRP-CIP Total Assets: Trading investments $ 5,961 $ 1,330 $ 60,810 $ 68,101 $ 5,069 $ 1,918 $ 6,987 Due from broker 285 202 4,923 5,410 181 294 475 Other assets 32 — 899 931 43 — 43 Total assets $ 6,278 $ 1,532 $ 66,632 $ 74,442 $ 5,293 $ 2,212 $ 7,505 Liabilities: Due to broker $ 35 $ — $ 3,168 $ 3,203 $ — $ — $ — Other liabilities and accrued expenses 87 5 199 291 70 5 75 Total liabilities $ 122 $ 5 $ 3,367 $ 3,494 $ 70 $ 5 $ 75 The following table summarizes the fair value of trading investments and equity method investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Trading Investments Equity Method Investments Trading Investments Equity Method Investments Voting Interest Entities ACOM $ — $ 6,115 $ — $ 6,371 CDF 6,755 — 5,702 — Variable Interest Entities GLI SICAV 5,961 — 5,069 — GRP-CIP 1,330 — 1,918 — GRP-TE — 61 — 88 SICAV Preferred 60,810 — — — Total $ 74,856 $ 6,176 $ 12,689 $ 6,459 Gain (loss) from trading investments—net for the years ended December 31, 2017, 2016 and 2015 , which represent realized and unrealized gains and losses recorded by the funds the Company consolidates, are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Voting Interest Entities CDF $ (417 ) $ 839 $ (2,167 ) LPX — (769 ) 6 Variable Interest Entities GLI SICAV 904 297 (135 ) GRP-CIP 309 (149 ) (80 ) SICAV Preferred 1,119 — — Gain (loss) from trading investments—net $ 1,915 $ 218 $ (2,376 ) Equity in earnings (losses) of affiliates—net for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Voting Interest Entities ACOM $ (256 ) $ 748 $ (1,988 ) LPX — 852 — MLO — 1,737 (8,397 ) Variable Interest Entities GRP-TE 14 (13 ) 7 Equity in earnings (losses) of affiliates—net $ (242 ) $ 3,324 $ (10,378 ) The following tables summarize the cost, gross unrealized gains, gross unrealized losses and fair value of available-for-sale investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 Cost Gross Unrealized Gains Gross (1) Fair Value Common stocks $ 6,782 $ 639 $ (183 ) $ 7,238 Company-sponsored funds 13,376 1,269 (13 ) 14,632 Fixed income securities 3,966 15 (20 ) 3,961 Preferred securities 1,100 29 (5 ) 1,124 Other 100 19 — 119 Total available-for-sale investments $ 25,324 $ 1,971 $ (221 ) $ 27,074 _________________________ (1) At December 31, 2017 , there were no securities with material unrealized losses continuously for a period of more than 12 months. December 31, 2016 Cost Gross Unrealized Gains Gross Unrealized Losses (1) Fair Value Common stocks $ 4,639 $ 194 $ (325 ) $ 4,508 Company-sponsored funds 28,232 1,755 (110 ) 29,877 Preferred securities 1,020 13 (22 ) 1,011 Total available-for-sale investments $ 33,891 $ 1,962 $ (457 ) $ 35,396 _________________________ (1) At December 31, 2016 , there were no securities with material unrealized losses continuously for a period of more than 12 months. Available-for-sale investments with a fair value of approximately $6,086,000 and $18,521,000 at December 31, 2017 and 2016, respectively, were in an unrealized loss position. As of December 31, 2017 and 2016, unrealized losses on available-for-sale investments were generally caused by changes in 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 as well as qualitative and quantitative information about the financial condition and near-term prospects of the issuers. As of December 31, 2017 and 2016, the Company determined that it had the ability and intent to hold the remaining available-for-sale investments for which no other-than-temporary impairment has occurred until a recovery of fair value. Accordingly, impairments of these investments were considered temporary. Sales proceeds, gross realized gains and gross realized losses from available-for-sale investments for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Proceeds from sales $ 25,812 $ 20,823 $ 7,298 Gross realized gains 714 1,879 759 Gross realized losses (367 ) (428 ) (3,407 ) (1) _________________________ (1) Includes other-than-temporary impairment charge of $2,846,000 related to the Company’s seed investment in RAP.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Accounting Standards 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 as of the beginning of the reporting period. There were no transfers between level 1 and level 2 during the year ended December 31, 2017 . The following table presents fair value measurements as of December 31, 2017 (in thousands): Level 1 Level 2 Level 3 Investments Measured at NAV (2) Total Cash equivalents (1) $ 173,270 $ — $ — $ — $ 173,270 Trading investments Common stocks $ 5,961 $ — $ — $ — $ 5,961 Fixed income securities — 6,755 — — 6,755 Limited partnership interests — — 605 725 1,330 Preferred securities 7,658 53,152 — — 60,810 Total trading investments $ 13,619 $ 59,907 $ 605 $ 725 $ 74,856 Equity method investments $ — $ — $ — $ 6,176 $ 6,176 Available-for-sale investments Common stocks $ 7,238 $ — $ — $ — 7,238 Company-sponsored funds 14,632 — — — 14,632 Fixed income securities — 3,961 — — 3,961 Preferred securities 999 125 — — 1,124 Other — — — 119 119 Total available-for-sale investments $ 22,869 $ 4,086 $ — $ 119 $ 27,074 Derivatives - assets Commodity contracts $ 487 $ — $ — $ — $ 487 Foreign exchange contracts — — — — — Total derivatives - assets $ 487 $ — $ — $ — $ 487 Derivatives - liabilities Commodity contracts $ 286 $ — $ — $ — $ 286 Foreign exchange contracts — 64 — — 64 Total derivatives - liabilities $ 286 $ 64 $ — $ — $ 350 _________________________ (1) Comprised of investments in actively traded U.S. Treasury money market funds measured at NAV. (2) Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position. Trading investments in fixed income securities classified as level 2 in the above table were comprised of U.S. Treasury Bills carried at amortized cost, which approximates fair value. Trading investments in preferred securities classified as level 2 were comprised of corporate debt and certain preferred securities. The fair value amounts were generally determined using third-party pricing services. The pricing services may utilize evaluated pricing models that vary by asset class and incorporate available trade, bid and other market information. Since these securities do not trade on a daily basis, the pricing services evaluate pricing applications and apply available information through processes such as yield curves, benchmarking of like securities, sector groupings, and matrix pricing, to prepare evaluations. 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 in limited partnership vehicles that invest in private equity vehicles that invest directly in real estate which was valued using a contractual selling price. Trading investments classified as investments measured at NAV (or its equivalent) as a practical expedient in the above table were comprised of limited partnership interests which represent the Company’s co-investments through GRP-CIP in limited partnership vehicles that invest in non-registered real estate funds, which are valued based on the NAVs of the underlying funds. As of December 31, 2017 , the Company did not have the ability to redeem these interests. Equity method investments classified as investments measured at NAV (or its equivalent) as a practical expedient in the above table were comprised of the Company’s partnership interests in ACOM and GRP-TE, which approximate their fair value based on the funds’ NAVs. ACOM invests indirectly in exchange-traded commodity futures contracts and other commodity-related derivatives through an investment in the Commodities Sub-Fund. The Company has the ability to redeem its investment in ACOM monthly at NAV with prior written notice of 5 days and there are no significant restrictions to redemption. GRP-TE invests in non-registered real estate funds and in private equity vehicles that invest directly in real estate. As of December 31, 2017 , the Company did not have the ability to redeem its investment in GRP-TE. Available-for-sale investments classified as level 2 in the above table were primarily comprised of corporate bonds and certain preferred securities whose fair values are generally determined using third-party pricing services. The pricing services may utilize pricing models, and inputs into those models may include reported trades, executable bid and ask prices, broker-dealer quotations, prices or yields of similar securities, benchmark curves and other market information. The pricing services may use a matrix approach, which considers information regarding securities with similar characteristics to determine the valuation for a security. Available-for-sale investments classified as investments measured at NAV (or its equivalent) as a practical expedient in the above table were comprised of the Company’s co-investment in a Cayman trust invested in global listed infrastructure securities. The following table presents fair value measurements as of December 31, 2016 (in thousands): Level 1 Level 2 Level 3 Investments Measured at NAV (2) Total Cash equivalents (1) $ 140,872 $ — $ — $ — $ 140,872 Trading investments Common stocks $ 5,069 $ — $ — $ — $ 5,069 Fixed income securities — 5,702 — — 5,702 Limited partnership interests — — 1,196 722 1,918 Total trading investments $ 5,069 $ 5,702 $ 1,196 $ 722 $ 12,689 Equity method investments $ — $ — $ — $ 6,459 $ 6,459 Available-for-sale investments Common stocks $ 4,508 $ — $ — $ — $ 4,508 Company-sponsored funds 29,877 — — — 29,877 Preferred securities 1,001 10 — — 1,011 Total available-for-sale investments $ 35,386 $ 10 $ — $ — $ 35,396 Derivatives - assets Commodity contracts $ 343 $ — $ — $ — $ 343 Foreign exchange contracts — 1,417 — — 1,417 Total derivatives - assets $ 343 $ 1,417 $ — $ — $ 1,760 Derivatives - liabilities Commodity contracts $ 266 $ — $ — $ — $ 266 Total derivatives - liabilities $ 266 $ — $ — $ — $ 266 _________________________ (1) Comprised of investments in actively traded U.S. Treasury money market funds measured at NAV. (2) Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position. Trading investments classified as level 2 in the above table were comprised of U.S. 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 in limited partnership vehicles that invest in private equity vehicles that invest directly in real estate which are generally valued using a discounted cash flow model. Trading investments classified as investments measured at NAV (or its equivalent) as a practical expedient in the above table were comprised of limited partnership interests which represent the Company’s co-investments through GRP-CIP in limited partnership vehicles that invest in non-registered real estate funds, which are valued based on the NAVs of the underlying funds. As of December 31, 2016 , the Company did not have the ability to redeem these interests. Equity method investments classified as investments measured at NAV (or its equivalent) as a practical expedient in the above table were comprised of the Company’s partnership interests in ACOM and GRP-TE, which approximate their fair value based on the funds’ NAVs. ACOM invested directly in exchange-traded commodity futures contracts and other commodity-related derivatives. The Company has the ability to redeem its investment in ACOM monthly at NAV with prior written notice of 5 days and there are no significant restrictions to redemption. GRP-TE invests in non-registered real estate funds and in private equity vehicles that invest directly in real estate. As of December 31, 2016 , the Company did not have the ability to redeem its investment in GRP-TE. The following table summarizes the changes in level 3 investments measured at fair value on a recurring basis for the years ended December 31, 2017 and 2016 (in thousands): Trading Investments Limited Partnership Interests Balance at January 1, 2016 $ 1,312 Purchases / contributions 51 Sales / distributions (53 ) Realized gains — Unrealized gains (losses) (1) (114 ) Transfers into (out of) level 3 — Balance at December 31, 2016 $ 1,196 Purchases / contributions 419 Sales / distributions (1,291 ) Realized gains 162 Unrealized gains (losses) (1) 119 Transfers into (out of) level 3 — Balance at December 31, 2017 $ 605 _________________________ (1) Pertains to unrealized gains (losses) from securities held at December 31, 2017 and 2016. Realized and unrealized gains (losses) from investments classified as trading investments in the above tables were recorded as gain (loss) from trading investments—net in the Company’s consolidated statements of operations. Valuation Techniques In certain instances, debt, equity and preferred securities are valued on the basis of prices from an orderly transaction between market participants provided by reputable broker-dealers or independent pricing services. In determining the value of a particular investment, independent 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 generally performs reviews of valuations provided by broker-dealers or independent pricing services. Investments in Company-sponsored funds are valued at their closing price or NAV (or its equivalent) as a practical expedient. 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 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. As of December 31, 2017 , the valuation technique used in the fair value measurement of the Company’s level 3 investment, limited partnership interests - direct investment in real estate, of approximately $605,000 was based on a contractual selling price. The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2016 were: Fair Value (in thousands) Fair Value Methodology Significant Unobservable Inputs Input / Range Limited partnership interests - direct investments in real estate $ 1,196 Discounted cash flows Discount rates Exit capitalization rates Market rental rates 11% - 12.5% 8% - 8.5% $14.00 - 17.00 psf Changes in the significant unobservable inputs in the above tables may result in a materially higher or lower fair value measurement.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2017
Derivatives [Abstract]
Derivatives	Derivatives The following tables summarize 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, 2017 and 2016 (in thousands): December 31, 2017 Assets Liabilities Notional Fair Value Notional Fair Value Total foreign exchange contracts $ — $ — $ 12,279 $ 64 Total commodity contracts 8,939 487 6,876 286 Total derivatives $ 8,939 $ 487 $ 19,155 $ 350 December 31, 2016 Assets Liabilities Notional Fair Value Notional Fair Value Total foreign exchange contracts $ 13,839 $ 1,417 $ — $ — Total commodity contracts 6,538 343 4,825 266 Total derivatives $ 20,377 $ 1,760 $ 4,825 $ 266 Securities included in trading investments on the consolidated statement of financial condition of approximately $414,000 and $487,000 as of December 31, 2017 and 2016, respectively, were held as collateral for futures contracts. Gains and losses from derivative financial instruments for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Foreign exchange contracts $ (1,481 ) $ 1,626 $ (702 ) Commodity contracts (438 ) 835 (2,167 ) Total derivatives $ (1,919 ) $ 2,461 $ (2,869 )

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment The following table summarizes the Company’s property and equipment as of December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Equipment $ 7,503 $ 6,969 Furniture and fixtures 3,598 3,505 Software 21,173 18,467 Leasehold improvements 16,017 16,031 Subtotal 48,291 44,972 Less: Accumulated depreciation and amortization (33,251 ) (29,008 ) Property and equipment, net $ 15,040 $ 15,964 Depreciation and amortization expense related to property and equipment was $4,229,000 , $4,155,000 and $3,827,000 for the years ended December 31, 2017, 2016 and 2015 , respectively. Depreciation and amortization expense related to property and equipment is recorded using the straight-line method over the estimated useful lives of the related assets which range from 3 - 7 years. Leasehold improvements are amortized using the straight-line method over the lease term.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
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 using the treasury stock method 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 and are excluded from the computation if their effect is anti-dilutive. There were no anti-dilutive common stock equivalents for the year ended December 31, 2017 . Anti-dilutive common stock equivalents of approximately 14,000 and 43,000 shares were excluded from the computation for the years ended December 31, 2016 and 2015, respectively. The following table 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, 2017, 2016 and 2015 (in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net income $ 92,486 $ 92,810 $ 64,337 Less: Net (income) loss attributable to redeemable noncontrolling interest (547 ) 126 214 Net income attributable to common stockholders $ 91,939 $ 92,936 $ 64,551 Basic weighted average shares outstanding 46,353 45,951 45,433 Dilutive potential shares from restricted stock units 626 481 464 Diluted weighted average shares outstanding 46,979 46,432 45,897 Basic earnings per share attributable to common stockholders $ 1.98 $ 2.02 $ 1.42 Diluted earnings per share attributable to common stockholders $ 1.96 $ 2.00 $ 1.41

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
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 20.0 million shares of common stock may be granted under the SIP. At December 31, 2017 , RSUs with respect to approximately 14.9 million shares of common stock had been issued under the SIP. Total compensation cost related to unvested RSUs not yet recognized was approximately $36,092,000 at December 31, 2017 and is expected to be recognized over approximately the next three years. In January 2018, the Company granted approximately 0.7 million restricted stock units under the SIP with a grant date fair value of $29,274,000 which vest over a four year period. Restricted Stock Units Vested Restricted Stock Unit Grants The Company granted awards of vested RSUs to the non-management 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 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 generally delivered ratably over four years. At December 31, 2017 , vested RSUs with respect to approximately 42,000 shares of common stock were outstanding pursuant to these grants. In connection with the grant of these vested RSUs to employees, the Company recorded non-cash stock-based compensation expense of approximately $618,000 , $486,000 and $425,000 for the years ended December 31, 2017, 2016 and 2015 , respectively. The following table sets forth activity relating to the Company’s awards of vested RSUs under the SIP to the non-management directors and certain employees (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 28 $ 34.93 Granted 12 35.31 Delivered (10 ) 31.86 Balance at December 31, 2015 30 36.17 Granted 13 37.17 Delivered (9 ) 34.02 Balance at December 31, 2016 34 37.15 Granted 16 38.14 Delivered (8 ) 40.03 Balance at December 31, 2017 42 36.98 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. Dividend equivalents are accrued on unvested RSUs for all dividends declared by the Company and are forfeitable until they are delivered. The dividend equivalents will generally vest and be delivered on the fourth anniversary of the original grant date. At December 31, 2017 , RSUs with respect to approximately 318,000 shares of common stock were outstanding pursuant to these grants. Amortization expense related to the unearned stock-based compensation, net of forfeitures, was approximately $3,957,000 , $4,685,000 and $5,233,000 for the years ended December 31, 2017, 2016 and 2015 , respectively. The following table sets forth activity relating to the Company’s awards of unvested RSUs under the SIP to certain employees (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 690 $ 26.72 Granted 73 41.10 Delivered (461 ) 26.95 Forfeited (6 ) 40.52 Balance at December 31, 2015 296 36.36 Granted 159 30.31 Delivered (147 ) 35.52 Forfeited (1 ) 42.09 Balance at December 31, 2016 307 33.62 Granted 151 35.45 Delivered (140 ) 34.41 Balance at December 31, 2017 318 34.14 Incentive Bonus Plans for Employees of the Company The Company has implemented a program for employees which, based upon compensation levels, automatically allocates a portion of their year-end bonuses in the form of unvested RSUs (Mandatory Program). Dividend equivalents are accrued on unvested RSUs for all dividends declared by the Company and are forfeitable until they are delivered. The RSUs under the Mandatory Program will vest and be delivered ratably over four years and the dividend equivalents will generally vest and be delivered on the fourth anniversary of the original grant date. The fair value at the date of grant of the RSUs under the Mandatory Program is expensed on a straight-line basis over the vesting period. As of December 31, 2017 , approximately 1,550,000 RSUs under the Mandatory Program including dividend equivalents were outstanding. Amortization expense, net of forfeitures, related to the unearned stock-based compensation under the Mandatory Program, was approximately $17,175,000 , $16,847,000 and $17,315,000 for the years ended December 31, 2017, 2016 and 2015 , respectively. The following table sets forth activity relating to the Company’s incentive bonus plans, including dividend equivalents (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 1,454 $ 34.04 Granted 496 41.45 Delivered (607 ) 32.69 Forfeited (61 ) 38.51 Balance at December 31, 2015 1,282 37.33 Granted 722 30.02 Delivered (548 ) 35.86 Forfeited (57 ) 35.14 Balance at December 31, 2016 1,399 34.22 Granted 714 35.36 Delivered (523 ) 34.80 Forfeited (40 ) 33.87 Balance at December 31, 2017 1,550 34.60 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 fair 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 is 600,000 . For the years ended December 31, 2017, 2016 and 2015 , approximately 18,000 , 19,000 and 19,000 shares, respectively, were purchased by eligible employees through the ESPP. For the years ended December 31, 2017, 2016 and 2015 , the Company recorded a non-cash stock-based compensation expense of approximately $112,000 , $114,000 and $95,000 , respectively, which represents the discount on the shares issued pursuant to this plan. The ESPP will terminate upon the earliest to occur of (1) termination of the ESPP by the board of directors or (2) issuance of all of the shares reserved for issuance under the ESPP. The board of directors is authorized to increase the number of shares available for issuance under ESPP.

401(k) and Profit-Sharing Plan

401(k) and Profit-Sharing Plan	12 Months Ended
	Dec. 31, 2017
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 eligible 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, 2017, 2016 and 2015 . 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, 2017, 2016 and 2015 totaled approximately $128,000 , $126,000 and $118,000 , respectively. Matching contributions, net of forfeitures, to the Plan for the years ended December 31, 2017, 2016 and 2015 totaled approximately $1,715,000 , $1,464,000 and $1,511,000 , respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company is an investment adviser to, and has administration 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, 2017, 2016 and 2015 (in thousands): Year Ended December 31, 2017 2016 2015 Investment advisory and administration fees $ 245,232 $ 227,184 $ 218,942 Distribution and service fees 20,156 19,396 16,001 $ 265,388 $ 246,580 $ 234,943 Sales proceeds, gross realized gains, gross realized losses and dividend income from available-for-sale investments in Company-sponsored funds for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Proceeds from sales $ 15,105 $ 13,251 $ — Gross realized gains 80 1,159 — Gross realized losses, including other-than-temporary impairment — — (2,846 ) Dividend income 675 787 250 The Company has agreements with certain affiliated open-end and closed-end funds to reimburse certain fund expenses. For the years ended December 31, 2017, 2016 and 2015 , expenses of approximately $10,403,000 , $8,568,000 and $8,676,000 , 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, 2017 and 2016 are receivables due from Company-sponsored funds of approximately $23,666,000 and $20,221,000 , respectively.

Regulatory Requirements

Regulatory Requirements	12 Months Ended
	Dec. 31, 2017
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 by the Rule. As of December 31, 2017 , CSS had net capital of approximately $ 3,530,000 , which exceeded its requirements by approximately $ 3,271,000 . 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 SEC Rule 15c3-3 pursuant to provisions (k)(1) and (k)(2)(i) of such rule. CSAL and CSUK are regulated outside the U.S. by the Hong Kong Securities and Futures Commission and the United Kingdom Financial Conduct Authority, respectively. As of December 31, 2017 , CSAL and CSUK had aggregate regulatory capital of approximately $ 63,235,000 , which exceeded aggregate regulatory capital requirements by approximately $ 58,641,000 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
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 March 2024. The Company also leases certain information technology applications, market data and office equipment under noncancelable operating leases expiring at various dates through July 2020. The aggregate minimum future payments under the leases are as follows (in thousands): Year Ending December 31, Operating Leases 2018 $ 13,897 2019 13,473 2020 11,966 2021 10,863 2022 10,863 Thereafter 11,828 $ 72,890 Rent expense charged to operations, including escalation charges for real estate taxes and other expenses, totaled approximately $11,811,000 , $11,535,000 and $11,215,000 for the years ended December 31, 2017, 2016 and 2015 , 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 remainder of which is made through GRP-CIP for up to 12 years through the life of GRP-TE. As of December 31, 2017 , the Company has funded approximately $3.8 million with respect to this commitment. The actual timing for funding the unfunded portion of this commitment is currently unknown, as the drawdown of the Company’s unfunded 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, 2017 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (the Tax Act) was enacted. The Tax Act, among other things, imposed a one-time tax on deemed repatriated accumulated earnings and profits of the Company’s foreign subsidiaries, moves from the current system of worldwide taxation to a territorial system and reduced the statutory corporate tax rate to 21% . As a result of these changes, in the fourth quarter of 2017, the Company recorded a transition tax attributable to the shift in tax regimes and also remeasured its deferred and other tax balances using enacted tax rates which will be in effect when such items are expected to reverse. Tax charges in connection with the enactment of the Tax Act may change due to, among other things, additional guidance that may be issued by the U.S. Department of the Treasury with respect to the Tax Act and revisions to the Company’s assumptions as further information and interpretations become available. The provision for income taxes for the years ended December 31, 2017, 2016 and 2015 included U.S. federal, state, local and foreign taxes. The effective tax rate for the year ended December 31, 2017 was approximately 42.5% , which differed from the U.S. federal statutory rate primarily due to tax charges of approximately $8.4 million related to the transition tax on the deemed repatriation of foreign earnings and profits and approximately $4.3 million related to the remeasurement of deferred and other tax balances, partially offset by the release of certain tax reserves and other tax-related items aggregating to approximately $4.6 million . The effective tax rate for the year ended December 31, 2016 was approximately 35.3% , which differed from the U.S. federal statutory rate primarily due to the release of a valuation allowance associated with unrealized gains on the Company’s seed investments. The effective tax rate was approximately 42.9% for the year ended December 31, 2015 . The $8.4 million transition tax liability is payable over eight years starting in March 2019. The table below summarizes the Company’s future commitments: Year Ending December 31, Transition Tax Liability 2019 $ 675 2020 675 2021 675 2022 675 2023 675 2024 1,265 2025 1,686 2026 2,106 $ 8,432 The income before provision for income taxes and provision for income taxes for the years ended December 31, 2017, 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Income before provision for income taxes - U.S. $ 149,338 $ 132,882 $ 101,007 Income before provision for income taxes - Non-U.S. 11,062 10,521 11,737 Total income before provision for income taxes $ 160,400 $ 143,403 $ 112,744 Current taxes: U.S. federal $ 58,082 $ 42,056 $ 32,065 State and local 8,155 7,423 6,442 Non-U.S. 1,991 2,014 2,508 68,228 51,493 41,015 Deferred taxes: U.S. federal (428 ) (743 ) 6,334 State and local (412 ) (86 ) 1,273 Non-U.S. 526 (71 ) (215 ) (314 ) (900 ) 7,392 Provision for income taxes $ 67,914 $ 50,593 $ 48,407 Deferred income taxes, which have been remeasured to reflect the lower statutory corporate tax rate resulting from the Tax Act, 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, 2017 and 2016 consist of the following (in thousands): At December 31, 2017 2016 Deferred income tax assets (liabilities): Stock-based compensation $ 5,437 $ 7,797 Non-deductible realized losses on investments 1,030 2,685 Dividend equivalents on unvested restricted stock units 1,715 2,686 Net unrealized losses on investments 2,359 4,101 Deferred compensation (1,325 ) (4,528 ) Deferred rent 1,488 2,407 Other (996 ) (2,743 ) Subtotal 9,708 12,405 Less: valuation allowance (3,896 ) (6,786 ) Deferred income tax asset—net $ 5,812 $ 5,619 The Company had capital loss carryforwards of approximately $4,181,000 and $6,959,000 for the years ended December 31, 2017 and 2016 which, if unused, will expire in years 2018 to 2021. The valuation allowance on the net deferred income tax asset decreased approximately $2,890,000 during the year ended December 31, 2017 . At December 31, 2017 , the Company had approximately $12,406,000 of total gross unrecognized tax benefits. Of this total, approximately $9,532,000 (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 believes it is reasonably possible that it will reduce its unrecognized tax benefits by $1,975,000 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, 2015 $ 6,346 Addition for tax positions of current year 1,147 Addition for tax positions of prior years 250 Reduction of tax positions from prior years (484 ) Gross unrecognized tax benefits balance at December 31, 2015 $ 7,259 Addition for tax positions of current year 1,437 Addition for tax positions of prior years 163 Reduction of tax positions from prior years (1,007 ) Gross unrecognized tax benefits balance at December 31, 2016 $ 7,852 Addition for tax positions of current year 1,724 Addition for tax positions of prior years 6,624 Reduction of tax positions from prior years (3,794 ) Gross unrecognized tax benefits balance at December 31, 2017 $ 12,406 The Company records potential interest and penalties related to uncertain tax positions in the provision for income taxes. At December 31, 2017 and 2016, the Company had approximately $1,933,000 and $2,250,000 , respectively, in potential interest and penalties associated with uncertain tax positions. The tax years 2011 through 2017 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, 2017, 2016 and 2015 is as follows: Year Ended December 31, 2017 2016 2015 U.S. statutory tax rate 35.0 % 35.0 % 35.0 % Tax Act 8.0 % — % — % State and local income taxes, net of federal income taxes 3.1 % 3.5 % 4.3 % Non-deductible losses on investments 0.2 % 1.3 % 5.2 % Reserve adjustments (1.9 )% (0.2 )% — % Non-taxable gains on investments (0.2 )% (3.0 )% — % Foreign operations tax differential (1.4 )% (1.1 )% (2.1 )% Other (0.3 )% (0.2 )% 0.5 % Effective income tax rate 42.5 % 35.3 % 42.9 %

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2017
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 funds and third-party institutional separate account subadvisory relationship, which is comprised of multiple accounts, provided 10% or more of the total revenue of the Company (in thousands): Year Ended December 31, 2017 2016 2015 Cohen & Steers Realty Shares, Inc. (CSR): Investment advisory and administration fees $ 38,392 $ 45,047 $ 47,870 Percent of total revenue 10 % 13 % 15 % Cohen & Steers Preferred Securities and Income Fund, Inc. (CPX): Investment advisory and administration fees $ 54,523 $ 43,797 $ 29,212 Percent of total revenue 14 % 13 % 9 % Daiwa Asset Management: Investment advisory fees $ 37,756 $ 39,377 $ 37,653 Portfolio consulting and other 3,035 2,930 2,793 Total $ 40,791 $ 42,307 $ 40,446 Percent of total revenue 11 % 12 % 12 % The table below presents revenue by client domicile for the years ended December 31, 2017, 2016 and 2015 (in thousands): Year Ended December 31, 2017 2016 2015 North America $ 313,408 $ 285,896 $ 269,766 Japan 42,303 43,458 41,899 Asia excluding Japan 11,496 9,852 6,624 Europe 10,987 10,670 10,366 Total $ 378,194 $ 349,876 $ 328,655

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unadudited)	Selected Quarterly Financial Data (unaudited) The table below presents selected quarterly financial data for 2017 and 2016 (in thousands, except per share data): Quarter 1st 2nd 3rd 4th Total 2017 Revenue $ 89,686 $ 92,812 $ 96,354 $ 99,342 $ 378,194 Operating income 35,528 37,357 40,973 40,888 154,746 Net income attributable to common stockholders 22,985 23,474 25,082 20,398 91,939 Earnings per share attributable to common stockholders: Basic 0.50 0.51 0.54 0.44 1.98 Diluted 0.49 0.50 0.53 0.43 1.96 Weighted-average shares outstanding: Basic 46,243 46,373 46,386 46,407 46,353 Diluted 46,603 46,902 47,047 47,300 46,979 2016 Revenue $ 79,681 $ 86,373 $ 94,388 $ 89,434 $ 349,876 Operating income 28,307 34,131 37,213 35,860 135,511 Net income attributable to common stockholders 18,083 24,808 23,877 26,168 92,936 Earnings per share attributable to common stockholders: Basic 0.39 0.54 0.52 0.57 2.02 Diluted 0.39 0.53 0.51 0.56 2.00 Weighted-average shares outstanding: Basic 45,808 45,984 45,999 46,010 45,951 Diluted 46,195 46,378 46,544 46,609 46,432

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
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 require disclosure and/or adjustment. On February 22, 2018, CNS declared a quarterly dividend on its common stock in the amount of $0.33 per share. This dividend will be payable on March 22, 2018 to stockholders of record at the close of business on March 8, 2018.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements —In March 2016, the Financial Accounting Standards Board (FASB) issued new guidance amending the current accounting for an investment that becomes qualified for the equity method of accounting. The guidance requires that the cost of acquiring an additional interest in the investment, if any, that resulted in it qualifying for the equity method be added to the carrying value of the investment. The equity method will then be applied from that point forward without any retroactive application or adjustment. This new guidance was effective for the Company’s first quarter of 2017. The adoption of this new guidance did not have a material impact on its consolidated financial statements and related disclosures. In March 2016, the FASB issued new guidance which simplifies several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, excess tax benefits, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company adopted this guidance on January 1, 2017. As a result, the Company reclassified $285,000 from additional paid-in capital to retained earnings on January 1, 2017. Prospectively beginning January 1, 2017, excess tax benefits or tax deficiencies are now reflected in the consolidated statements of operations as a component of the provision for income taxes. For the year ended December 31, 2017, the Company recognized $49,000 of excess tax benefits. Additionally, the consolidated statements of cash flows now reflect excess tax benefits from share-based payments as an operating activity, rather than a financing activity. Finally, the Company elected to account for forfeitures as they occur, rather than estimate expected forfeitures.
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.
Consolidation of Company-sponsored Funds	Consolidation of Company-sponsored Funds —Investments in Company-sponsored funds and management fees are evaluated at inception and thereafter, if there is a reconsideration event, in order to determine whether to apply the Variable Interest Entity (VIE) model or the Voting Interest Entity (VOE) model. In performing this analysis, all of the Company’s management fees are presumed to be commensurate and at market and are therefore not considered variable interests. 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 (a) the power to direct the activities of the VIE that most significantly affect its performance and (b) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE. 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 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. VIEs for which the Company is deemed to be the primary beneficiary are consolidated. Investments in Company-sponsored funds that are determined to be VOEs are consolidated when the Company’s ownership interest is greater than 50% of the outstanding voting interests of the fund or when the Company is the general partner of the fund and the limited partners do not have substantive kick-out or participating rights in the fund. The Company records noncontrolling interests in consolidated funds for which the Company’s ownership is less than 100% .
Cash and Cash Equivalents	Cash and Cash Equivalents —Cash and cash equivalents are on deposit with three major financial institutions and consist of short-term, highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
Due from/to Brokers	Due from/to Brokers —The Company conducts business, primarily with respect to 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 contractual agreements. The due from/to brokers balance represents cash and cash equivalents balances at brokers/custodians and/or receivables and payables for unsettled securities 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 management and approved 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 represent seed investments in which the Company owns between 20 - 50% of the outstanding voting interests in the affiliated fund or when it is determined that the Company is able to exercise significant influence but not control over the investments. When using the equity method, the Company recognizes its respective share of the affiliated investee fund net income or loss for the period which is recorded as equity in earnings (losses) of affiliates—net in the Company’s consolidated statements of operations. As of December 31, 2017 , the Company’s equity method investments consisted of interests in affiliated funds measured at fair value based on quoted market prices or NAV (or its equivalent) as a practical expedient 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, fixed income securities, investment-grade preferred instruments and investments in Company-sponsored open-end funds where the Company has neither control nor the ability to exercise significant influence. 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, based on available quantitative and qualitative information as of the report date, the loss will be recognized as gain (loss) from available-for-sale investments—net in the Company’s consolidated statements of operations. 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 based on their settlement price at the close of trading on the associated commodities exchange or board of trade 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 on the Company’s consolidated statements of financial condition. As of December 31, 2017 , 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 certain client receivables. These instruments are measured at fair value with gains and losses recorded in other non-operating income (loss) 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 on 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 funds. This interest is redeemable at the option of the investors and therefore is not treated as permanent equity. Redeemable noncontrolling interest is recorded 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 and closed-end funds. Investment advisory fees are earned pursuant to the terms of investment management agreements and are based on a contractual fee rate applied to the assets in the portfolio. The Company also earns administration fees from certain Company-sponsored open-end 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 fee revenue is recognized when earned.
Distribution and Service Fee Revenue	Distribution and Service Fee Revenue —Distribution and service fee revenue is based on the average daily net assets of certain share classes of the Company’s sponsored open-end funds distributed by CSS. Distribution and service fee revenue is earned daily and is generally recorded gross of any third-party distribution and service fee expense for applicable share classes.
Distribution and Service Fee Expense	Distribution and Service Fee Expense —Distribution and service fee expense includes distribution fees, shareholder servicing fees and intermediary assistance payments. Distribution and service fee expense is recorded on an accrual basis. Distribution fee expense represents payments made to qualified intermediaries for (i) assistance in connection with the distribution of the Company’s sponsored open-end 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). The Company pays distribution fee expense based on the average daily net assets under management of certain share classes of certain of the funds. Shareholder servicing fee expense represents payments made to qualified intermediaries for shareholder account service and maintenance. These services are provided pursuant to written agreements with such qualified institutions. The Company pays shareholder serving fee expense generally based on the average assets under management or the number of accounts being serviced. Intermediary assistance payments represent payments to qualified intermediaries for activities related to distribution, shareholder servicing and marketing and support of Company-sponsored open-end funds and are incremental to those described above. Intermediary assistance payments are generally based on the average assets under management or the number of accounts being serviced.
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 strategy accounts, (ii) earning a licensing fee for the use of the Company’s proprietary indexes 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 when earned.
Stock-based Compensation	Stock-based Compensation —The Company recognizes compensation expense for the grant-date fair value of awards of equity instruments to employees. This expense is recognized over the period during which employees are required to provide service. Forfeitures are recorded as incurred.
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. The calculation of tax liabilities involves dealing with uncertainties in the application of complex tax laws and regulations in a multitude of jurisdictions across the Company’s global operations. A tax benefit from an uncertain tax position may be recognized when it is more likely than not that the position will be sustained upon examination, including resolution of any related appeals or litigation processes, on the basis of the technical merits. The Company records potential interest and penalties related to uncertain tax positions in the provision for income taxes in the consolidated statements of operations.
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 of such subsidiaries 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.
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, as well as the net of tax amounts attributable to foreign currency translation gain (loss), unrealized gain (loss) from available-for-sale investments and the reclassification of realized gain (loss) from available-for-sale investments to the statements of operations.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements —In February 2018, the FASB issued new guidance allowing entities to reclassify certain tax effects related to the enactment of the Tax Act from accumulated other comprehensive income (AOCI) to retained earnings. Prior to the issuance of the new guidance, a portion of the previously recognized deferred tax effects recorded in AOCI was “left stranded” in AOCI as the effect of remeasuring the deferred taxes using the reduced federal corporate income tax rate was required to be recorded through income. The new guidance allows these stranded tax effects to be reclassified from AOCI to retained earnings. The new guidance will be effective on January 1, 2019, with early adoption permitted and is to be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is still assessing which adoption method it will choose but it does not expect either method to have a material effect on its consolidated financial statements and related disclosures. In August 2017, the FASB issued new guidance amending the accounting for hedging activities. The new guidance (i) expands hedge accounting for nonfinancial and financial risk components and amends measurement methodologies to more closely align hedge accounting with an entity’s risk management activities, (ii) decreases the complexity of preparing and understanding hedge results through eliminating the separate measurement and reporting of hedge ineffectiveness, (iii) enhances transparency, comparability and understandability of hedge results through enhanced disclosures and changing the presentation of hedge results to align the effects of the hedging instrument and the hedged item and (iv) reduces the cost and complexity of applying hedge accounting by simplifying the manner in which assessments of hedge effectiveness may be performed. The new guidance will be effective on January 1, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this new guidance on its consolidated financial statements and related disclosures. In May 2017, the FASB issued new guidance for modification accounting related to share-based payment transactions in order to provide clarity and to reduce current diversity in practice. This new guidance does not fundamentally change the notion of a modification. Instead, the amendments clarify which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments became effective on January 1, 2018 and must be applied prospectively to any awards modified on or after the adoption date. The adoption of the new guidance did not have a material effect on the Company’s consolidated financial statements and related disclosures. In January 2017, the FASB issued guidance to simplify the goodwill impairment test by removing the requirement to perform a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. This new guidance will be effective on January 1, 2020. The Company does not expect the adoption of the new guidance to have a material effect on its consolidated financial statements and related disclosures. In August 2016, the FASB amended the current guidance on the classification of certain cash receipts and payments in the statement of cash flows. This guidance is intended to unify the currently diverse presentations and classifications, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. The Company evaluated the eight issues and concluded that only distributions received from equity method investees is applicable to the Company. This amended guidance became effective on January 1, 2018 and was adopted retrospectively. The Company made an accounting policy election to use the Cumulative Earnings Approach when determining whether distributions received from equity method investments should be classified as either operating or investing activities within the Company’s consolidated statements of cash flows. In February 2016, the FASB issued guidance introducing a new lease model which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. The new guidance establishes a right-of-use model (ROU) that requires a lessee to recognize an ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The new guidance also requires disclosures by lessees and lessors to enable users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The new guidance is effective on January 1, 2019, with early adoption permitted. The Company expects to adopt the new guidance on its effective date. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Company is continuing to assess the effect of adoption, it currently believes the most significant change relates to the recognition of new ROU assets and lease liabilities on its consolidated statements of financial condition for its office space and other operating leases. The Company does not expect a significant change in its leasing activity between now and adoption. The Company is still assessing which of the available practical expedients it plans to elect upon adoption. In January 2016, the FASB issued new guidance amending the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. Upon adoption of this guidance, changes in the fair value of the Company’s available-for-sale equity investments will be reported through earnings rather than through other comprehensive income. This new guidance became effective on January 1, 2018 and required a cumulative-effect adjustment to beginning retained earnings in the amount of approximately $1,323,000 , net of tax. Additionally, if the Company had applied the new guidance for the year ended December 31, 2017, approximately $250,000 of net unrealized gains recorded in other comprehensive income would have been recorded in non-operating income (loss) in the Company’s consolidated statement of operations. 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. In March 2016, the FASB issued a revision which clarifies (a) determination of the appropriate unit of account under the revenue standard’s principal versus agent guidance and (b) application of the indicators of whether an entity is a principal or an agent in accordance with the revenue standard’s control principle. In April 2016, the FASB issued an amendment to provide more detailed guidance and examples related to (a) identifying performance obligations and (b) licenses of intellectual property. In May 2016, the FASB amended the standard to clarify the guidance on assessing collectibility, presenting sales taxes, measuring noncash consideration, and certain transition matters. This new guidance became effective for the Company’s first quarter of 2018 and was adopted retrospectively. The adoption of the new standard did not have a material impact on the timing of recognition for the majority of the Company’s revenue but will affect the presentation of certain costs on either a gross or net basis. In addition, the adoption of the new standard will require additional disclosures in 2018.
Valuation Techniques	Valuation Techniques In certain instances, debt, equity and preferred securities are valued on the basis of prices from an orderly transaction between market participants provided by reputable broker-dealers or independent pricing services. In determining the value of a particular investment, independent 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 generally performs reviews of valuations provided by broker-dealers or independent pricing services. Investments in Company-sponsored funds are valued at their closing price or NAV (or its equivalent) as a practical expedient. 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 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 Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Goodwill and Intangible Assets	The following table summarizes the changes in the Company’s goodwill and intangible assets during the years ended December 31, 2017 and 2016 (in thousands): Goodwill Finite-Lived Intangible Assets Indefinite-Lived Intangible Assets Balance at January 1, 2016 $ 17,975 $ 273 $ 1,250 Currency revaluation (291 ) — — Amortization N/A (89 ) N/A Balance at December 31, 2016 $ 17,684 $ 184 $ 1,250 Currency revaluation 1,350 — — Amortization N/A (89 ) N/A Balance at December 31, 2017 $ 19,034 $ 95 $ 1,250
Schedule of Intangible Assets	The following table summarizes the Company’s intangible assets at December 31, 2017 and 2016 (in thousands): Remaining Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Intangible Assets, Net 2017 Amortized intangible assets: Client relationships 12 $ 1,543 $ (1,448 ) $ 95 Non-amortized intangible assets: Mutual fund management contracts — 1,250 — 1,250 Total $ 2,793 $ (1,448 ) $ 1,345 2016 Amortized intangible assets: Client relationships 24 $ 1,543 $ (1,359 ) $ 184 Non-amortized intangible assets: Mutual fund management contracts — 1,250 — 1,250 Total $ 2,793 $ (1,359 ) $ 1,434
Schedule Future Amortization Expense	The remaining future amortization expense is summarized in the table below (in thousands): Period Ending December 31, Remaining Amortization Expense 2018 $ 95

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments [Abstract]
Summary of Investment Holdings	The following table summarizes the Company’s investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Trading investments $ 74,856 $ 12,689 Equity method investments 6,176 6,459 Available-for-sale investments 27,074 35,396
Gain (Loss) on Investments	Gain (loss) from seed investments for the years ended December 31, 2017, 2016 and 2015 is summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Gain (loss) from trading investments—net (1) $ 1,915 $ 218 $ (2,376 ) Equity in earnings (losses) of affiliates—net (242 ) 3,324 (10,378 ) Gain (loss) from available-for-sale investments—net 347 1,451 (2,648 ) Number of new funds seeded 2 — 2 _________________________ (1) Includes net income (loss) attributable to redeemable noncontrolling interest for the periods presented.
Schedule of Variable Interest Entities	The following table represents the portion of the consolidated statements of financial condition attributable to the consolidated VIEs as of December 31, 2017 and 2016. The assets may only be used to settle obligations of each VIE and the liabilities are the sole obligation of each VIE, for which creditors do not have recourse to the general credit of the Company (in thousands): December 31, 2017 December 31, 2016 GLI SICAV GRP-CIP SICAV Preferred Total GLI SICAV GRP-CIP Total Assets: Trading investments $ 5,961 $ 1,330 $ 60,810 $ 68,101 $ 5,069 $ 1,918 $ 6,987 Due from broker 285 202 4,923 5,410 181 294 475 Other assets 32 — 899 931 43 — 43 Total assets $ 6,278 $ 1,532 $ 66,632 $ 74,442 $ 5,293 $ 2,212 $ 7,505 Liabilities: Due to broker $ 35 $ — $ 3,168 $ 3,203 $ — $ — $ — Other liabilities and accrued expenses 87 5 199 291 70 5 75 Total liabilities $ 122 $ 5 $ 3,367 $ 3,494 $ 70 $ 5 $ 75
Summary of Fair Value of Trading Investments and Equity Method Investments	The following table summarizes the fair value of trading investments and equity method investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Trading Investments Equity Method Investments Trading Investments Equity Method Investments Voting Interest Entities ACOM $ — $ 6,115 $ — $ 6,371 CDF 6,755 — 5,702 — Variable Interest Entities GLI SICAV 5,961 — 5,069 — GRP-CIP 1,330 — 1,918 — GRP-TE — 61 — 88 SICAV Preferred 60,810 — — — Total $ 74,856 $ 6,176 $ 12,689 $ 6,459
Gain (Loss) from Trading Investments	Gain (loss) from trading investments—net for the years ended December 31, 2017, 2016 and 2015 , which represent realized and unrealized gains and losses recorded by the funds the Company consolidates, are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Voting Interest Entities CDF $ (417 ) $ 839 $ (2,167 ) LPX — (769 ) 6 Variable Interest Entities GLI SICAV 904 297 (135 ) GRP-CIP 309 (149 ) (80 ) SICAV Preferred 1,119 — — Gain (loss) from trading investments—net $ 1,915 $ 218 $ (2,376 )
Schedule of Equity in Earnings (Losses) of Affiliates	Equity in earnings (losses) of affiliates—net for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Voting Interest Entities ACOM $ (256 ) $ 748 $ (1,988 ) LPX — 852 — MLO — 1,737 (8,397 ) Variable Interest Entities GRP-TE 14 (13 ) 7 Equity in earnings (losses) of affiliates—net $ (242 ) $ 3,324 $ (10,378 )
Schedule of Available-for-Sale Investments Reconciliation	The following tables summarize the cost, gross unrealized gains, gross unrealized losses and fair value of available-for-sale investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 Cost Gross Unrealized Gains Gross (1) Fair Value Common stocks $ 6,782 $ 639 $ (183 ) $ 7,238 Company-sponsored funds 13,376 1,269 (13 ) 14,632 Fixed income securities 3,966 15 (20 ) 3,961 Preferred securities 1,100 29 (5 ) 1,124 Other 100 19 — 119 Total available-for-sale investments $ 25,324 $ 1,971 $ (221 ) $ 27,074 _________________________ (1) At December 31, 2017 , there were no securities with material unrealized losses continuously for a period of more than 12 months. December 31, 2016 Cost Gross Unrealized Gains Gross Unrealized Losses (1) Fair Value Common stocks $ 4,639 $ 194 $ (325 ) $ 4,508 Company-sponsored funds 28,232 1,755 (110 ) 29,877 Preferred securities 1,020 13 (22 ) 1,011 Total available-for-sale investments $ 33,891 $ 1,962 $ (457 ) $ 35,396 _________________________ (1) At December 31, 2016 , there were no securities with material unrealized losses continuously for a period of more than 12 months.
Schedule of Realized Gains (Losses) on Available-for-sale investments	ales proceeds, gross realized gains and gross realized losses from available-for-sale investments for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Proceeds from sales $ 25,812 $ 20,823 $ 7,298 Gross realized gains 714 1,879 759 Gross realized losses (367 ) (428 ) (3,407 ) (1) _________________________ (1) Includes other-than-temporary impairment charge of $2,846,000 related to the Company’s seed investment in RAP.

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements, Recurring and Nonrecurring	The following table presents fair value measurements as of December 31, 2017 (in thousands): Level 1 Level 2 Level 3 Investments Measured at NAV (2) Total Cash equivalents (1) $ 173,270 $ — $ — $ — $ 173,270 Trading investments Common stocks $ 5,961 $ — $ — $ — $ 5,961 Fixed income securities — 6,755 — — 6,755 Limited partnership interests — — 605 725 1,330 Preferred securities 7,658 53,152 — — 60,810 Total trading investments $ 13,619 $ 59,907 $ 605 $ 725 $ 74,856 Equity method investments $ — $ — $ — $ 6,176 $ 6,176 Available-for-sale investments Common stocks $ 7,238 $ — $ — $ — 7,238 Company-sponsored funds 14,632 — — — 14,632 Fixed income securities — 3,961 — — 3,961 Preferred securities 999 125 — — 1,124 Other — — — 119 119 Total available-for-sale investments $ 22,869 $ 4,086 $ — $ 119 $ 27,074 Derivatives - assets Commodity contracts $ 487 $ — $ — $ — $ 487 Foreign exchange contracts — — — — — Total derivatives - assets $ 487 $ — $ — $ — $ 487 Derivatives - liabilities Commodity contracts $ 286 $ — $ — $ — $ 286 Foreign exchange contracts — 64 — — 64 Total derivatives - liabilities $ 286 $ 64 $ — $ — $ 350 _________________________ (1) Comprised of investments in actively traded U.S. Treasury money market funds measured at NAV. (2) Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position.	The following table presents fair value measurements as of December 31, 2016 (in thousands): Level 1 Level 2 Level 3 Investments Measured at NAV (2) Total Cash equivalents (1) $ 140,872 $ — $ — $ — $ 140,872 Trading investments Common stocks $ 5,069 $ — $ — $ — $ 5,069 Fixed income securities — 5,702 — — 5,702 Limited partnership interests — — 1,196 722 1,918 Total trading investments $ 5,069 $ 5,702 $ 1,196 $ 722 $ 12,689 Equity method investments $ — $ — $ — $ 6,459 $ 6,459 Available-for-sale investments Common stocks $ 4,508 $ — $ — $ — $ 4,508 Company-sponsored funds 29,877 — — — 29,877 Preferred securities 1,001 10 — — 1,011 Total available-for-sale investments $ 35,386 $ 10 $ — $ — $ 35,396 Derivatives - assets Commodity contracts $ 343 $ — $ — $ — $ 343 Foreign exchange contracts — 1,417 — — 1,417 Total derivatives - assets $ 343 $ 1,417 $ — $ — $ 1,760 Derivatives - liabilities Commodity contracts $ 266 $ — $ — $ — $ 266 Total derivatives - liabilities $ 266 $ — $ — $ — $ 266 _________________________ (1) Comprised of investments in actively traded U.S. Treasury money market funds measured at NAV. (2) Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position.
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, 2017 and 2016 (in thousands): Trading Investments Limited Partnership Interests Balance at January 1, 2016 $ 1,312 Purchases / contributions 51 Sales / distributions (53 ) Realized gains — Unrealized gains (losses) (1) (114 ) Transfers into (out of) level 3 — Balance at December 31, 2016 $ 1,196 Purchases / contributions 419 Sales / distributions (1,291 ) Realized gains 162 Unrealized gains (losses) (1) 119 Transfers into (out of) level 3 — Balance at December 31, 2017 $ 605 _________________________ (1) Pertains to unrealized gains (losses) from securities held at December 31, 2017 and 2016.
Fair Value Measurements, Valuation Techniques		The valuation techniques and significant unobservable inputs used in the fair value measurement of the following level 3 investments as of December 31, 2016 were: Fair Value (in thousands) Fair Value Methodology Significant Unobservable Inputs Input / Range Limited partnership interests - direct investments in real estate $ 1,196 Discounted cash flows Discount rates Exit capitalization rates Market rental rates 11% - 12.5% 8% - 8.5% $14.00 - 17.00 psf

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivatives [Abstract]
Schedule of Derivative Instruments	The notional amount represents the absolute value amount of all outstanding derivative contracts as of December 31, 2017 and 2016 (in thousands): December 31, 2017 Assets Liabilities Notional Fair Value Notional Fair Value Total foreign exchange contracts $ — $ — $ 12,279 $ 64 Total commodity contracts 8,939 487 6,876 286 Total derivatives $ 8,939 $ 487 $ 19,155 $ 350	December 31, 2016 Assets Liabilities Notional Fair Value Notional Fair Value Total foreign exchange contracts $ 13,839 $ 1,417 $ — $ — Total commodity contracts 6,538 343 4,825 266 Total derivatives $ 20,377 $ 1,760 $ 4,825 $ 266
Gains (Losses) on Derivatives	Gains and losses from derivative financial instruments for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Foreign exchange contracts $ (1,481 ) $ 1,626 $ (702 ) Commodity contracts (438 ) 835 (2,167 ) Total derivatives $ (1,919 ) $ 2,461 $ (2,869 )

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	The following table summarizes the Company’s property and equipment as of December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Equipment $ 7,503 $ 6,969 Furniture and fixtures 3,598 3,505 Software 21,173 18,467 Leasehold improvements 16,017 16,031 Subtotal 48,291 44,972 Less: Accumulated depreciation and amortization (33,251 ) (29,008 ) Property and equipment, net $ 15,040 $ 15,964

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table 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, 2017, 2016 and 2015 (in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net income $ 92,486 $ 92,810 $ 64,337 Less: Net (income) loss attributable to redeemable noncontrolling interest (547 ) 126 214 Net income attributable to common stockholders $ 91,939 $ 92,936 $ 64,551 Basic weighted average shares outstanding 46,353 45,951 45,433 Dilutive potential shares from restricted stock units 626 481 464 Diluted weighted average shares outstanding 46,979 46,432 45,897 Basic earnings per share attributable to common stockholders $ 1.98 $ 2.02 $ 1.42 Diluted earnings per share attributable to common stockholders $ 1.96 $ 2.00 $ 1.41

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
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 awards of vested RSUs under the SIP to the non-management directors and certain employees (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 28 $ 34.93 Granted 12 35.31 Delivered (10 ) 31.86 Balance at December 31, 2015 30 36.17 Granted 13 37.17 Delivered (9 ) 34.02 Balance at December 31, 2016 34 37.15 Granted 16 38.14 Delivered (8 ) 40.03 Balance at December 31, 2017 42 36.98 The following table sets forth activity relating to the Company’s incentive bonus plans, including dividend equivalents (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 1,454 $ 34.04 Granted 496 41.45 Delivered (607 ) 32.69 Forfeited (61 ) 38.51 Balance at December 31, 2015 1,282 37.33 Granted 722 30.02 Delivered (548 ) 35.86 Forfeited (57 ) 35.14 Balance at December 31, 2016 1,399 34.22 Granted 714 35.36 Delivered (523 ) 34.80 Forfeited (40 ) 33.87 Balance at December 31, 2017 1,550 34.60 The following table sets forth activity relating to the Company’s awards of unvested RSUs under the SIP to certain employees (share data in thousands): Number of Shares Weighted Average Grant Date Fair Value Balance at January 1, 2015 690 $ 26.72 Granted 73 41.10 Delivered (461 ) 26.95 Forfeited (6 ) 40.52 Balance at December 31, 2015 296 36.36 Granted 159 30.31 Delivered (147 ) 35.52 Forfeited (1 ) 42.09 Balance at December 31, 2016 307 33.62 Granted 151 35.45 Delivered (140 ) 34.41 Balance at December 31, 2017 318 34.14

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Sales proceeds, gross realized gains, gross realized losses and dividend income from available-for-sale investments in Company-sponsored funds for the years ended December 31, 2017, 2016 and 2015 are summarized in the table below (in thousands): Year Ended December 31, 2017 2016 2015 Proceeds from sales $ 15,105 $ 13,251 $ — Gross realized gains 80 1,159 — Gross realized losses, including other-than-temporary impairment — — (2,846 ) Dividend income 675 787 250 The following table sets forth the amount of revenue the Company earned from these affiliated funds for the years ended December 31, 2017, 2016 and 2015 (in thousands): Year Ended December 31, 2017 2016 2015 Investment advisory and administration fees $ 245,232 $ 227,184 $ 218,942 Distribution and service fees 20,156 19,396 16,001 $ 265,388 $ 246,580 $ 234,943

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The Company also leases certain information technology applications, market data and office equipment under noncancelable operating leases expiring at various dates through July 2020. The aggregate minimum future payments under the leases are as follows (in thousands): Year Ending December 31, Operating Leases 2018 $ 13,897 2019 13,473 2020 11,966 2021 10,863 2022 10,863 Thereafter 11,828 $ 72,890

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Transition Tax Liability, Fiscal Year Maturity Schedule	The $8.4 million transition tax liability is payable over eight years starting in March 2019. The table below summarizes the Company’s future commitments: Year Ending December 31, Transition Tax Liability 2019 $ 675 2020 675 2021 675 2022 675 2023 675 2024 1,265 2025 1,686 2026 2,106 $ 8,432
Schedule of Income before Taxes	The income before provision for income taxes and provision for income taxes for the years ended December 31, 2017, 2016 and 2015 are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Income before provision for income taxes - U.S. $ 149,338 $ 132,882 $ 101,007 Income before provision for income taxes - Non-U.S. 11,062 10,521 11,737 Total income before provision for income taxes $ 160,400 $ 143,403 $ 112,744 Current taxes: U.S. federal $ 58,082 $ 42,056 $ 32,065 State and local 8,155 7,423 6,442 Non-U.S. 1,991 2,014 2,508 68,228 51,493 41,015 Deferred taxes: U.S. federal (428 ) (743 ) 6,334 State and local (412 ) (86 ) 1,273 Non-U.S. 526 (71 ) (215 ) (314 ) (900 ) 7,392 Provision for income taxes $ 67,914 $ 50,593 $ 48,407
Components of Deferred Tax Assets and Liabilities	Significant components of the Company’s net deferred income tax asset at December 31, 2017 and 2016 consist of the following (in thousands): At December 31, 2017 2016 Deferred income tax assets (liabilities): Stock-based compensation $ 5,437 $ 7,797 Non-deductible realized losses on investments 1,030 2,685 Dividend equivalents on unvested restricted stock units 1,715 2,686 Net unrealized losses on investments 2,359 4,101 Deferred compensation (1,325 ) (4,528 ) Deferred rent 1,488 2,407 Other (996 ) (2,743 ) Subtotal 9,708 12,405 Less: valuation allowance (3,896 ) (6,786 ) Deferred income tax asset—net $ 5,812 $ 5,619
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, 2015 $ 6,346 Addition for tax positions of current year 1,147 Addition for tax positions of prior years 250 Reduction of tax positions from prior years (484 ) Gross unrecognized tax benefits balance at December 31, 2015 $ 7,259 Addition for tax positions of current year 1,437 Addition for tax positions of prior years 163 Reduction of tax positions from prior years (1,007 ) Gross unrecognized tax benefits balance at December 31, 2016 $ 7,852 Addition for tax positions of current year 1,724 Addition for tax positions of prior years 6,624 Reduction of tax positions from prior years (3,794 ) Gross unrecognized tax benefits balance at December 31, 2017 $ 12,406
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, 2017, 2016 and 2015 is as follows: Year Ended December 31, 2017 2016 2015 U.S. statutory tax rate 35.0 % 35.0 % 35.0 % Tax Act 8.0 % — % — % State and local income taxes, net of federal income taxes 3.1 % 3.5 % 4.3 % Non-deductible losses on investments 0.2 % 1.3 % 5.2 % Reserve adjustments (1.9 )% (0.2 )% — % Non-taxable gains on investments (0.2 )% (3.0 )% — % Foreign operations tax differential (1.4 )% (1.1 )% (2.1 )% Other (0.3 )% (0.2 )% 0.5 % Effective income tax rate 42.5 % 35.3 % 42.9 %

Concentration of Credit Risk (T

Concentration of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017, 2016 and 2015 (in thousands): Year Ended December 31, 2017 2016 2015 North America $ 313,408 $ 285,896 $ 269,766 Japan 42,303 43,458 41,899 Asia excluding Japan 11,496 9,852 6,624 Europe 10,987 10,670 10,366 Total $ 378,194 $ 349,876 $ 328,655 The following affiliated funds and third-party institutional separate account subadvisory relationship, which is comprised of multiple accounts, provided 10% or more of the total revenue of the Company (in thousands): Year Ended December 31, 2017 2016 2015 Cohen & Steers Realty Shares, Inc. (CSR): Investment advisory and administration fees $ 38,392 $ 45,047 $ 47,870 Percent of total revenue 10 % 13 % 15 % Cohen & Steers Preferred Securities and Income Fund, Inc. (CPX): Investment advisory and administration fees $ 54,523 $ 43,797 $ 29,212 Percent of total revenue 14 % 13 % 9 % Daiwa Asset Management: Investment advisory fees $ 37,756 $ 39,377 $ 37,653 Portfolio consulting and other 3,035 2,930 2,793 Total $ 40,791 $ 42,307 $ 40,446 Percent of total revenue 11 % 12 % 12 %

Selected Quarterly Financial 39

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The table below presents selected quarterly financial data for 2017 and 2016 (in thousands, except per share data): Quarter 1st 2nd 3rd 4th Total 2017 Revenue $ 89,686 $ 92,812 $ 96,354 $ 99,342 $ 378,194 Operating income 35,528 37,357 40,973 40,888 154,746 Net income attributable to common stockholders 22,985 23,474 25,082 20,398 91,939 Earnings per share attributable to common stockholders: Basic 0.50 0.51 0.54 0.44 1.98 Diluted 0.49 0.50 0.53 0.43 1.96 Weighted-average shares outstanding: Basic 46,243 46,373 46,386 46,407 46,353 Diluted 46,603 46,902 47,047 47,300 46,979 2016 Revenue $ 79,681 $ 86,373 $ 94,388 $ 89,434 $ 349,876 Operating income 28,307 34,131 37,213 35,860 135,511 Net income attributable to common stockholders 18,083 24,808 23,877 26,168 92,936 Earnings per share attributable to common stockholders: Basic 0.39 0.54 0.52 0.57 2.02 Diluted 0.39 0.53 0.51 0.56 2.00 Weighted-average shares outstanding: Basic 45,808 45,984 45,999 46,010 45,951 Diluted 46,195 46,378 46,544 46,609 46,432

Summary of Significant Accoun40

Summary of Significant Accounting Policies Consolidation (Details)	Dec. 31, 2017
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 Accoun41

Summary of Significant Accounting Policies Schedule of less than wholly owned subsidiaries (Details)	12 Months Ended
	Dec. 31, 2017
Maximum
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Minimum
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	50.00%

Summary of Significant Accoun42

Summary of Significant Accounting Policies Cumulative Translation Adjustments Balance (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Translation Adjustment
Cumulative Translation Adjustments balance [Line Items]
Cumulative Foreign Currency Translation Adjustment, Net of Tax	$ (4,781)	$ (6,845)	$ (3,908)

Summary of Significant Accoun43

Summary of Significant Accounting Policies New Accountings Pronouncements (Details)	12 Months Ended
	Dec. 31, 2017USD ($)
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefits	$ 49,000
Additional Paid-in Capital | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	285,000
Retained Earnings | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	1,323,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 250,000

Goodwill and Intangible Asset44

Goodwill and Intangible Assets - Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Beginning balance	$ 17,684	$ 17,975
Currency revaluation	1,350	(291)
Ending balance	19,034	17,684	$ 17,975
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross			273
Amortization	(89)	(89)	(89)
Finite-Lived Intangible Assets	95	184
Indefinite-Lived Intangible Assets
Fund management contracts	$ 1,250	$ 1,250	$ 1,250

Goodwill and Intangible Asset45

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization Period Remaining	12 months	24 months
Client relationships, Gross Carrying Amount			$ 273
Client relationships, Accumulated Amortization	$ (1,448)	$ (1,359)
Client relationships, Net	95	184
Fund management contracts	1,250	1,250	$ 1,250
Gross Carrying Amount	2,793	2,793
Intangible assets—net	1,345	1,434
Client Relationships
Finite-Lived Intangible Assets [Line Items]
Client relationships, Gross Carrying Amount	1,543	1,543
Client relationships, Accumulated Amortization	(1,448)	(1,359)
Client relationships, Net	95	184
Fund Management Contracts Member
Finite-Lived Intangible Assets [Line Items]
Fund management contracts	$ 1,250	$ 1,250

Goodwill and Intangible Asset46

Goodwill and Intangible Assets - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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]
2,018	95
Total	$ 95	$ 184

Investments Trading, Equity Met

Investments Trading, Equity Method Investments and Available-for-Sale Investments (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2017USD ($)new_funds_seeded		Dec. 31, 2016USD ($)new_funds_seeded		Dec. 31, 2015USD ($)new_funds_seeded
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other-than-temporary impairment, available-for-sale investments		$ 2,846
Available-for-sale investments, unrealized loss position, fair value		6,086		$ 18,521
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments	[1],[2]	74,856		12,689
Equity method investments		6,176		6,459
Available-for-sale investments		27,074		35,396
Gain (loss) from trading investments—net	[3]	1,915		218		$ (2,376)
Equity in earnings (losses) of affiliates—net		(242)		3,324		(10,378)
Gain (loss) from available-for-sale investments—net		$ 347		$ 1,451		$ (2,648)
Number of new funds seeded | new_funds_seeded		2		0		2
Available-for-sale investments [Abstract]
Cost		$ 25,324		$ 33,891
Gross Unrealized Gains		1,971		1,962
Gross Unrealized Losses		(221)	[4]	(457)	[5]
Fair Value		27,074		35,396
Proceeds from investing activities [Abstract]
Proceeds from sales		25,812		20,823		$ 7,298
Gross realized gains		714		1,879		759
Gross realized losses		$ (367)		(428)		(3,407)	[6]
ACOM
Schedule of Trading Securities and Other Trading Assets [Line Items]
Equity method investments, Ownership Percentage range		11.59%
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		$ 0		0
Equity method investments		6,115		6,371
Equity in earnings (losses) of affiliates—net		(256)		748		(1,988)
CDF
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		6,755		5,702
Equity method investments		0		0
Gain (loss) from trading investments—net		(417)		839		(2,167)
GLI SICAV
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		5,961		5,069
Equity method investments		0		0
Gain (loss) from trading investments—net		904		297		(135)
GRP-CIP
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		1,330		1,918
Equity method investments		0		0
Gain (loss) from trading investments—net		$ 309		(149)		(80)
GRP-TE
Schedule of Trading Securities and Other Trading Assets [Line Items]
Equity method investments, Ownership Percentage range		0.20%
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		$ 0		0
Equity method investments		61		88
Equity in earnings (losses) of affiliates—net		$ 14		(13)		7
SICAV Preferred
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Security, Ownership Percentage		26.00%
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		$ 60,810		0
Equity method investments		0		0
Gain (loss) from trading investments—net		1,119		0		0
LPX
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Gain (loss) from trading investments—net		0		(769)		6
Equity in earnings (losses) of affiliates—net		0		852		0
MLO
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Equity in earnings (losses) of affiliates—net		0		1,737		$ (8,397)
Preferred securities
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		1,124		1,011
Available-for-sale investments [Abstract]
Cost		1,100		1,020
Gross Unrealized Gains		29		13
Gross Unrealized Losses		(5)	[4]	(22)	[5]
Fair Value		1,124		1,011
Other
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		119
Available-for-sale investments [Abstract]
Cost		100
Gross Unrealized Gains		19
Gross Unrealized Losses	[4]	0
Fair Value		119
Common stocks
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		7,238		4,508
Available-for-sale investments [Abstract]
Cost		6,782		4,639
Gross Unrealized Gains		639		194
Gross Unrealized Losses		(183)	[4]	(325)	[5]
Fair Value		7,238		4,508
Company-sponsored funds
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		14,632		29,877
Available-for-sale investments [Abstract]
Cost		13,376		28,232
Gross Unrealized Gains		1,269		1,755
Gross Unrealized Losses		(13)	[4]	(110)	[5]
Fair Value		14,632		$ 29,877
Fixed income securities
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		3,961
Available-for-sale investments [Abstract]
Cost		3,966
Gross Unrealized Gains		15
Gross Unrealized Losses	[4]	(20)
Fair Value		$ 3,961
[1]	Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2017 and 2016 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund, Cohen & Steers Co-Investment Partnership, L.P. and Cohen & Steers SICAV Global Preferred Securities Fund, which were variable interest entities as of December 31, 2017 and 2016, respectively.
[2]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.
[3]	Includes net income (loss) attributable to redeemable noncontrolling interest for the periods presented.
[4]	At December 31, 2017, there were no securities with material unrealized losses continuously for a period of more than 12 months.
[5]	At December 31, 2016, there were no securities with material unrealized losses continuously for a period of more than 12 months.
[6]	ncludes other-than-temporary impairment charge of $2,846,000 related to the Company’s seed investment in RAP.

Investments Variable Interest E

Investments Variable Interest Entity (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Trading investments	[1],[2]	$ 74,856	$ 12,689
Due from broker	[1]	6,429	1,579
Other assets	[1]	7,053	7,382
Total assets		410,125	333,728
Due to broker	[1]	3,282	0
Other liabilities and accrued expenses	[1]	10,025	9,672
Total liabilities		86,794	67,061
GLI SICAV
Variable Interest Entity [Line Items]
Trading investments		5,961	5,069
Due from broker		285	181
Other assets		32	43
Total assets		6,278	5,293
Due to broker		35	0
Other liabilities and accrued expenses		87	70
Total liabilities		122	70
GRP-CIP
Variable Interest Entity [Line Items]
Trading investments		1,330	1,918
Due from broker		202	294
Other assets		0	0
Total assets		1,532	2,212
Due to broker		0	0
Other liabilities and accrued expenses		5	5
Total liabilities		5	5
SICAV Preferred
Variable Interest Entity [Line Items]
Trading investments		60,810
Due from broker		4,923
Other assets		899
Total assets		66,632
Due to broker		3,168
Other liabilities and accrued expenses		199
Total liabilities		3,367
GLI SICAV, GRP-CIP and SICAV Preferred
Variable Interest Entity [Line Items]
Trading investments		68,101
Due from broker		5,410
Other assets		931
Total assets		74,442
Due to broker		3,203
Other liabilities and accrued expenses		291
Total liabilities		$ 3,494
GLI SICAV and GRP-CIP
Variable Interest Entity [Line Items]
Trading investments			6,987
Due from broker			475
Other assets			43
Total assets			7,505
Due to broker			0
Other liabilities and accrued expenses			75
Total liabilities			$ 75
[1]	Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2017 and 2016 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund, Cohen & Steers Co-Investment Partnership, L.P. and Cohen & Steers SICAV Global Preferred Securities Fund, which were variable interest entities as of December 31, 2017 and 2016, respectively.
[2]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments	[1],[2]	$ 74,856	$ 12,689
Equity method investments		6,176	6,459
Available-for-sale investments		27,074	35,396
Common stocks
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		7,238	4,508
Company-sponsored funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		14,632	29,877
Fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		3,961
Fixed income securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		3,961
Fixed income securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0
Fixed income securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		3,961
Fixed income securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0
Preferred securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		1,124	1,011
Preferred securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		60,810
Available-for-sale investments		1,124	1,011
Preferred securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		7,658
Available-for-sale investments		999
Preferred securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		53,152
Available-for-sale investments		125
Preferred securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0
Available-for-sale investments		0
Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		119
Other | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		119
Other | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0
Other | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0
Other | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0
Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[3],[4]	0	0
Cash equivalents | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	[4]	173,270	140,872
Cash equivalents | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	[4]	173,270	140,872
Cash equivalents | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	[4]	0	0
Cash equivalents | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Cash equivalents	[4]	0	0
Trading investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	725	722
Trading investments | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		74,856	12,689
Trading investments | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		13,619	5,069
Trading investments | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		59,907	5,702
Trading investments | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		605	1,196
Trading investments | Limited partnership interests | Level 3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issuances, Settlements [Abstract]
Level 3 Fair Value		$ 605	$ 1,196
Trading investments | Limited partnership interests | Level 3 | Minimum
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issuances, Settlements [Abstract]
Fair Value Inputs, Discount Rates			11.00%
Fair Value Inputs, Exit Capitalization Rate			8.00%
Fair Value Inputs, Market Rental Rates			14
Trading investments | Limited partnership interests | Level 3 | Maximum
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issuances, Settlements [Abstract]
Fair Value Inputs, Discount Rates			12.50%
Fair Value Inputs, Exit Capitalization Rate			8.50%
Fair Value Inputs, Market Rental Rates			17
Trading investments | Limited partnership interests | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		$ 1,330	$ 1,918
Trading investments | Limited partnership interests | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Trading investments | Limited partnership interests | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Trading investments | Limited partnership interests | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		605	1,196
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		1,196	1,312
Purchases / contributions		419	51
Sales / distributions		(1,291)	(53)
Realized gains		162	0
Unrealized gains (losses)	[6]	119	(114)
Transfers into (out of) level 3		0	0
Ending Balance		605	1,196
Trading investments | Common stocks | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		5,961	5,069
Trading investments | Common stocks | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		5,961	5,069
Trading investments | Common stocks | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Trading investments | Common stocks | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Trading investments | Fixed income securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		6,755	5,702
Trading investments | Fixed income securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Trading investments | Fixed income securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		6,755	5,702
Trading investments | Fixed income securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Trading investments		0	0
Common stocks
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Limited partnership interests
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	725	722
Equity Method Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	6,176	6,459
Equity Method Investments | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Equity method investments		6,176	6,459
Equity Method Investments | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Equity method investments		0	0
Equity Method Investments | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Equity method investments		0	0
Equity Method Investments | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Equity method investments		0	0
Available-for-sale investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	119	0
Available-for-sale investments | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		27,074	35,396
Available-for-sale investments | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		22,869	35,386
Available-for-sale investments | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		4,086	10
Available-for-sale investments | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0	0
Available-for-sale investments | Common stocks | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		7,238	4,508
Available-for-sale investments | Common stocks | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		7,238	4,508
Available-for-sale investments | Common stocks | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0	0
Available-for-sale investments | Common stocks | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0	0
Available-for-sale investments | Company-sponsored funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		14,632	29,877
Available-for-sale investments | Company-sponsored funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		14,632	29,877
Available-for-sale investments | Company-sponsored funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0	0
Available-for-sale investments | Company-sponsored funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments		0	0
Available-for-sale investments | Preferred securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments			1,001
Available-for-sale investments | Preferred securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments			10
Available-for-sale investments | Preferred securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Available-for-sale investments			0
Company-sponsored funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Preferred securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	119
Derivative assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Derivative assets | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Derivative assets | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Derivative assets | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		487	1,760
Derivative - liabilities			266
Derivative assets | Fair Value, Measurements, Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	1,417
Derivative assets | Fair Value, Measurements, Recurring | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		487	343
Derivative assets | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		487	343
Derivative assets | Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	0
Derivative assets | Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		487	343
Derivative assets | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	1,417
Derivative assets | Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	1,417
Derivative assets | Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	0
Derivative assets | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	0
Derivative assets | Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	0
Derivative assets | Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - assets		0	0
Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Derivative liabilities | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0
Derivative liabilities | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Investments Measured at NAV	[5]	0	0
Derivative liabilities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		350
Derivative liabilities | Fair Value, Measurements, Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		64
Derivative liabilities | Fair Value, Measurements, Recurring | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		286	266
Derivative liabilities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		286	266
Derivative liabilities | Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		0
Derivative liabilities | Fair Value, Measurements, Recurring | Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		286	266
Derivative liabilities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		64	0
Derivative liabilities | Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		64
Derivative liabilities | Fair Value, Measurements, Recurring | Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		0	0
Derivative liabilities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		0	0
Derivative liabilities | Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		0
Derivative liabilities | Fair Value, Measurements, Recurring | Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Derivative - liabilities		$ 0	$ 0
[1]	Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2017 and 2016 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund, Cohen & Steers Co-Investment Partnership, L.P. and Cohen & Steers SICAV Global Preferred Securities Fund, which were variable interest entities as of December 31, 2017 and 2016, respectively.
[2]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.
[3]	Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position.
[4]	Comprised of investments in actively traded U.S. Treasury money market funds measured at NAV.
[5]	Comprised of certain investments measured at fair value using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented on the consolidated statement of financial position.
[6]	Pertains to unrealized gains (losses) from securities held at December 31, 2017 and 2016.

Derivatives (Details)

Derivatives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (1,919)	$ 2,461		$ (2,869)
Derivative Assets, Notional Amount	8,939	20,377
Derivative Assets, Fair Value	487	1,760
Derivative Liabilities, Notional Amount	19,155	4,825
Derivative Liabilities, Fair Value	350	266
Trading investments
Derivative [Line Items]
Trading investment and held as collateral	414	487	[1]
Foreign exchange contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,481)	1,626		(702)
Derivative Assets, Notional Amount	0	13,839
Derivative Assets, Fair Value	0	1,417
Derivative Liabilities, Notional Amount	12,279	0
Derivative Liabilities, Fair Value	64	0
Commodity contracts
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(438)	835		$ (2,167)
Derivative Assets, Notional Amount	8,939	6,538
Derivative Assets, Fair Value	487	343
Derivative Liabilities, Notional Amount	6,876	4,825
Derivative Liabilities, Fair Value	$ 286	$ 266
[1]	Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2017 and 2016, respectively.

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment [Line Items]
Depreciation and amortization	$ 4,229	$ 4,155	$ 3,827
Property and equipment, gross	48,291	44,972
Accumulated depreciation and amortization	(33,251)	(29,008)
Property and equipment, net	$ 15,040	15,964
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	$ 7,503	6,969
Furniture and fixtures
Property and Equipment [Line Items]
Property and equipment, gross	3,598	3,505
Software
Property and Equipment [Line Items]
Property and equipment, gross	21,173	18,467
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	$ 16,017	$ 16,031

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Anti-dilutive common stock equivalents excluded from computation (in shares)									0	14	43
Net income									$ 92,486	$ 92,810	$ 64,337
Less: Net (income) loss attributable to redeemable noncontrolling interest									(547)	126	214
Net income attributable to common stockholders	$ 20,398	$ 25,082	$ 23,474	$ 22,985	$ 26,168	$ 23,877	$ 24,808	$ 18,083	$ 91,939	$ 92,936	$ 64,551
Basic weighted average shares outstanding (in shares)	46,407	46,386	46,373	46,243	46,010	45,999	45,984	45,808	46,353	45,951	45,433
Dilutive potential shares from restricted stock units (in shares)									626	481	464
Diluted weighted average shares outstanding (in shares)	47,300	47,047	46,902	46,603	46,609	46,544	46,378	46,195	46,979	46,432	45,897
Basic earnings per share attributable to common stockholders (in dollars per share)	$ 0.44	$ 0.54	$ 0.51	$ 0.50	$ 0.57	$ 0.52	$ 0.54	$ 0.39	$ 1.98	$ 2.02	$ 1.42
Diluted earnings per share attributable to common stockholders (in dollars per share)	$ 0.43	$ 0.53	$ 0.50	$ 0.49	$ 0.56	$ 0.51	$ 0.53	$ 0.39	$ 1.96	$ 2	$ 1.41

Stock-Based Compensation Vested

Stock-Based Compensation Vested RSUs (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	51,104,593	50,415,152
Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 36,092
Stock Incentive Plan | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Authorized	20,000,000
Stock Incentive Plan | Restricted Stock Units (RSUs) | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued	14,900,000
Allocated Share-based Compensation Expense	$ 3,957	$ 4,685	$ 5,233
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)	34,000	30,000	28,000
Granted (shares)	16,000	13,000	12,000
Delivered (shares)	(8,000)	(9,000)	(10,000)
Balance at End of Period (shares)	42,000	34,000	30,000
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)	$ 37.15	$ 36.17	$ 34.93
Granted, Weighted Average Grant Date Fair Value (usd per share)	38.14	37.17	35.31
Delivered, Weighted Average Grant Date Fair Value (usd per share)	40.03	34.02	31.86
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	$ 36.98	$ 37.15	$ 36.17
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	$ 618	$ 486	$ 425
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)	42,000

Stock-Based Compensation Unvest

Stock-Based Compensation Unvested RSUs and Incentive Bonus Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	51,104,593	50,415,152
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans, Weighted Average Grant Date Fair Value [Roll Forward]
Employee stock purchase plans	18,000	19,000	19,000
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	$ 36,092,000
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)	307,000	296,000	690,000
Granted (shares)	151,000	159,000	73,000
Delivered (shares)	(140,000)	(147,000)	(461,000)
Forfeited (shares)		(1,000)	(6,000)
Balance at end of period (shares)	318,000	307,000	296,000
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)	$ 33.62	$ 36.36	$ 26.72
Granted, Weighted Average Grant Date Fair Value (usd per share)	35.45	30.31	41.10
Delivered, Weighted Average Grant Date Fair Value (usd per share)	34.41	35.52	26.95
Forfeited, Weighted Average Grant Date Fair Value (usd per share)		42.09	40.52
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	$ 34.14	$ 33.62	$ 36.36
Common stock, shares issued	14,900,000
Allocated Share-based Compensation Expense	$ 3,957,000	$ 4,685,000	$ 5,233,000
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)	$ 34.41	$ 35.52	$ 26.95
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)	$ 34.80	$ 35.86	$ 32.69
Share-based Compensation Arrangement by Share-based Payment Award, Incentive Bonus Plans [Roll Forward]
Balance at beginning of period (shares)	1,399,000	1,282,000	1,454,000
Granted (shares)	714,000	722,000	496,000
Delivered (shares)	523,000	548,000	(607,000)
Forfeited (shares)	(40,000)	(57,000)	(61,000)
Balance at end of period (shares)	1,550,000	1,399,000	1,282,000
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)	$ 34.22	$ 37.33	$ 34.04
Granted, Weighted Average Grant Date Fair Value (usd per share)	35.36	30.02	41.45
Delivered, Weighted Average Grant Date Fair Value (usd per share)	34.80	35.86	32.69
Forfeited, Weighted Average Grant Date Fair Value (usd per share)	33.87	35.14	38.51
Balance at end of period, Weighted Average Grant Date Fair Value (usd per share)	$ 34.60	$ 34.22	$ 37.33
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	1,550,000
Allocated Share-based Compensation Expense	$ 17,175,000	$ 16,847,000	$ 17,315,000
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	112,000	114,000	95,000
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	$ 618,000	$ 486,000	$ 425,000

401(k) and Profit-Sharing Plan

401(k) and Profit-Sharing Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	$ 128	$ 126	$ 118
Employer matching contributions	1,715	$ 1,464	$ 1,511
Common stock | Restricted Stock Units (RSUs)
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Allocated Share-based Compensation Expense	$ 36,092

Related Party Transactions (Det

Related Party Transactions (Details) - Affiliated Entity - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transactions Revenue [Abstract]
Investment advisory and administrative fees	$ 245,232	$ 227,184	$ 218,942
Distribution and service fees	20,156	19,396	16,001
Total	265,388	246,580	234,943
Related Party Transactions Summary [Abstract]
Proceeds from sales	15,105	13,251	0
Gross realized gains	80	1,159	0
Gross realized losses, including other-than-temporary impairment	0	0	(2,846)
Dividend income	675	787	250
Fund expenses, included in general and administrative expenses	10,403	8,568	$ 8,676
Receivables, company sponsored mutual funds	$ 23,666	$ 20,221

Regulatory Requirements (Detail

Regulatory Requirements (Details) $ in Thousands	Dec. 31, 2017USD ($)
Securities Registered Domestically
Regulatory Requirements
Net Capital	$ 3,530
Excess Capital	3,271
Foreign Country
Regulatory Requirements
Net Capital	63,235
Excess Capital	$ 58,641

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Commitments
Loss Contingencies [Line Items]
Long-term Purchase Commitments, Time Period	12 years
Commitment to invest
Loss Contingencies [Line Items]
Other Commitment	$ 5.1
Long-term committment, funded amount	$ 3.8

Commitments and Contingencies59

Commitments and Contingencies - Other Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Aggregate Minimum Future Payments [Line Items]
Rent expense	$ 11,811	$ 11,535	$ 11,215
Rent Obligations
Aggregate Minimum Future Payments [Line Items]
2,017	13,897
2,018	13,473
2,019	11,966
2,020	10,863
2,021	10,863
Thereafter	11,828
Other Commitment	$ 72,890

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective tax rate	42.50%	35.30%	42.90%
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Deferred Tax Liability	$ 8,432
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit)	4,300
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Other Tax Related Items, Provisional Income Tax Expense (Benefit)	4,600
Gross unrecognized tax benefits	12,406	$ 7,852	$ 7,259	$ 6,346
Unrecognized tax benefits that impact effective tax rate in future periods	9,532
Reduction in unrecognized tax benefits	1,975
Uncertain tax positions, accrued interest and penalties	$ 1,933	$ 2,250

Income Taxes - Schedule of Tran

Income Taxes - Schedule of Transition Tax Liabilities by Fiscal Year (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Income Tax Disclosure [Abstract]
2,019	$ 675
2,020	675
2,021	675
2,022	675
2,023	675
2,024	1,265
2,025	1,686
2,026	2,106
Total	$ 8,432

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income before provision for income taxes
U.S. income before provision for income taxes	$ 149,338	$ 132,882	$ 101,007
Foreign income before provision for income taxes	11,062	10,521	11,737
Income before provision for income taxes	160,400	143,403	112,744
Current taxes:
U.S. federal	58,082	42,056	32,065
State and local	8,155	7,423	6,442
Non-U.S.	1,991	2,014	2,508
Total	68,228	51,493	41,015
Deferred taxes:
U.S. federal	(428)	(743)	6,334
State and local	(412)	(86)	1,273
Non-U.S.	526	(71)	(215)
Deferred income taxes	(314)	(900)	7,392
Provision for income taxes	$ 67,914	$ 50,593	$ 48,407

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Stock-based compensation	$ 5,437	$ 7,797
Non-deductible realized loss on investments	1,030	2,685
Dividend equivalents on unvested restricted stock units	1,715	2,686
Deferred Tax Assets, Unrealized Losses on Trading Securities	2,359	4,101
Deferred compensation	(1,325)	(4,528)
Deferred rent	1,488	2,407
Other	(996)	(2,743)
Subtotal	9,708	12,405
Less: valuation allowance	(3,896)	(6,786)
Deferred income tax asset - net	5,812	5,619
Capital Loss Carryforward	4,181	$ 6,959
Changes in Valuation Allowance	$ 2,890

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Gross unrecognized tax benefits balance	$ 7,852	$ 7,259	$ 6,346
Addition for tax positions of current year	1,724	1,437	1,147
Addition for tax positions of prior years	6,624	163	250
Reduction of tax positions from prior years	(3,794)	(1,007)	(484)
Gross unrecognized tax benefits balance	$ 12,406	$ 7,852	$ 7,259

Income Taxes - Reconciliation65

Income Taxes - Reconciliation of Federal Statutory Income Tax Rate to Effective Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	35.00%	35.00%	35.00%
Tax Act	8.00%	0.00%	0.00%
State and local income taxes, net of federal income taxes	3.10%	3.50%	4.30%
Non-deductible loss on investments	0.20%	1.30%	5.20%
Reserve adjustments	(1.90%)	(0.20%)	(0.00%)
Non-taxable gain on investments	(0.20%)	(3.00%)	(0.00%)
Foreign operations tax differential	(1.40%)	(1.10%)	(2.10%)
Other	(0.30%)	(0.20%)	0.50%
Effective income tax rate	42.50%	35.30%	42.90%

Concentration of Credit Risk (D

Concentration of Credit Risk (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)financial_institution	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Concentration Risk (Line Items)
Revenues	$ 99,342	$ 96,354	$ 92,812	$ 89,686	$ 89,434	$ 94,388	$ 86,373	$ 79,681	$ 378,194	$ 349,876	$ 328,655
Number of financial institutions | financial_institution									3
Sales Revenue, Segment | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 378,194	349,876	328,655
Sales Revenue, Segment | United States | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									313,408	285,896	269,766
Sales Revenue, Segment | Japan | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									42,303	43,458	41,899
Sales Revenue, Segment | Other | Geographic Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 11,496	$ 9,852	$ 6,624
Cohen & Steers Realty Shares, Inc. (CSR) | Sales Revenue, Services | Customer Concentration Risk
Concentration Risk (Line Items)
Percent of total revenue									10.00%	13.00%	15.00%
Cohen & Steers Realty Shares, Inc. (CSR) | Sales Revenue, Services | Investment advisory and administration fees | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 38,392	$ 45,047	$ 47,870
Cohen & Steers Preferred Securities and Income Fund, Inc. (CPX) | Sales Revenue, Services | Customer Concentration Risk
Concentration Risk (Line Items)
Percent of total revenue									14.00%	13.00%	9.00%
Cohen & Steers Preferred Securities and Income Fund, Inc. (CPX) | Sales Revenue, Services | Investment advisory and administration fees | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 54,523	$ 43,797	$ 29,212
Daiwa Asset Management | Sales Revenue, Services | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 40,791	$ 42,307	$ 40,446
Percent of total revenue									11.00%	12.00%	12.00%
Daiwa Asset Management | Sales Revenue, Services | Investment advisory and administration fees | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 37,756	$ 39,377	$ 37,653
Daiwa Asset Management | Sales Revenue, Services | Portfolio consulting and other revenue | Customer Concentration Risk
Concentration Risk (Line Items)
Revenues									$ 3,035	$ 2,930	$ 2,793

Selected Quarterly Financial 67

Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 99,342	$ 96,354	$ 92,812	$ 89,686	$ 89,434	$ 94,388	$ 86,373	$ 79,681	$ 378,194	$ 349,876	$ 328,655
Operating income	40,888	40,973	37,357	35,528	35,860	37,213	34,131	28,307	154,746	135,511	127,549
Net income attributable to common stockholders	$ 20,398	$ 25,082	$ 23,474	$ 22,985	$ 26,168	$ 23,877	$ 24,808	$ 18,083	$ 91,939	$ 92,936	$ 64,551
Earnings per share attributable to common stockholders:
Basic (in dollars per share)	$ 0.44	$ 0.54	$ 0.51	$ 0.50	$ 0.57	$ 0.52	$ 0.54	$ 0.39	$ 1.98	$ 2.02	$ 1.42
Diluted (in dollars per share)	$ 0.43	$ 0.53	$ 0.50	$ 0.49	$ 0.56	$ 0.51	$ 0.53	$ 0.39	$ 1.96	$ 2	$ 1.41
Weighted-average shares outstanding:
Basic (shares)	46,407	46,386	46,373	46,243	46,010	45,999	45,984	45,808	46,353	45,951	45,433
Diluted (shares)	47,300	47,047	46,902	46,603	46,609	46,544	46,378	46,195	46,979	46,432	45,897

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	Feb. 22, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Dividends declared per share		$ 2.12	$ 1.54	$ 1.50
Dividend Declared | Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share	$ 0.33