Investments Trading, Equity Method Investments and Available-for-Sale Investments (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($) new_funds_seeded		Dec. 31, 2015 USD ($) new_funds_seeded		Dec. 31, 2014 USD ($) 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		18,521		$ 1,779
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments	[1],[2]	12,689		37,169
Equity method investments		6,459		16,974
Available-for-sale investments		35,396		17,191
Gain (loss) from trading investments—net	[3]	218		(2,376)		$ (1,567)
Equity in earnings (losses) of affiliates		3,324		(10,378)		(1,955)
Gain (loss) from available-for-sale investments—net		$ 1,451		$ (2,648)		$ 2,041
Number of new funds seeded | new_funds_seeded		0		2		1
Available-for-sale investments [Abstract]
Cost		$ 33,891		$ 17,127
Gross Unrealized Gains		1,962		355
Gross Unrealized Losses		(457)	[4]	(291)	[5]
Fair Value		35,396		17,191
Proceeds from investing activities [Abstract]
Proceeds from sales		20,823		7,298		$ 12,704
Gross realized gains		1,879		759		2,251
Gross realized losses, including other-than-temporary impairment		(428)		(3,407)	[6]	(210)
Equity Method Investments
Equity Method Investment, Summarized Financial Information [Abstract]
Total assets		105,946		147,590
Total liabilities		109		2,038
Net assets		105,837		145,552
Total revenue	[7]	5,163		2,753		2,896
Total expenses	[7]	1,609		1,194		2,019
Net realized gain (loss) and net change in unrealized appreciation (depreciation) on investments	[7]	10,201		(44,936)		(14,827)
Net income (loss)	[7]	$ 13,755		(43,377)		(13,950)
ACOM
Schedule of Trading Securities and Other Trading Assets [Line Items]
Ownership Percentage range		10.36%
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		$ 0		0
Equity method investments		6,371		5,624
Gain (loss) from trading investments—net		0		0		(505)
Equity in earnings (losses) of affiliates		748		(1,988)		(1,228)
CDF
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		5,702		5,606
Equity method investments		0		0
Gain (loss) from trading investments—net		839		(2,167)		(2,804)
GLI SICAV
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		5,069		4,719
Equity method investments		0		0
Gain (loss) from trading investments—net		297		(135)		0
GRP-CIP
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		1,918		2,131
Equity method investments		0		0
Gain (loss) from trading investments—net		$ (149)		(80)		151
GRP-TE
Schedule of Trading Securities and Other Trading Assets [Line Items]
Ownership Percentage range		0.20%
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		$ 0		0
Equity method investments		88		92
Equity in earnings (losses) of affiliates		(13)		7		11
Onshore Fund
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Gain (loss) from trading investments—net		0		0		24
Offshore Fund
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Equity in earnings (losses) of affiliates		0		0		20
LPX
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		0		24,713
Equity method investments		0		0
Gain (loss) from trading investments—net		(769)		6		0
Equity in earnings (losses) of affiliates		852		0		0
MLO
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Trading investments		0		0
Equity method investments		0		11,258
Gain (loss) from trading investments—net		0		0		1,567
Equity in earnings (losses) of affiliates		1,737		(8,397)		(1,511)
RAP
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Equity in earnings (losses) of affiliates		0		0		$ 753
Preferred securities
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		1,011		1,178
Available-for-sale investments [Abstract]
Cost		1,020		1,115
Gross Unrealized Gains		13		66
Gross Unrealized Losses		(22)	[4]	(3)	[5]
Fair Value		1,011		1,178
Common stocks
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		4,508		3,834
Available-for-sale investments [Abstract]
Cost		4,639		3,828
Gross Unrealized Gains		194		288
Gross Unrealized Losses		(325)	[4]	(282)	[5]
Fair Value		4,508		3,834
Company-sponsored funds
Trading, Equity Method Investments and Available-for-Sale Investments [Abstract]
Available-for-sale investments		29,877		12,179
Available-for-sale investments [Abstract]
Cost		28,232		12,184
Gross Unrealized Gains		1,755		1
Gross Unrealized Losses		(110)	[4]	(6)	[5]
Fair Value		$ 29,877		$ 12,179

[1] Asset and liability amounts in parentheses represent the aggregated balances at December 31, 2016 and December 31, 2015 attributable to Cohen & Steers SICAV Global Listed Infrastructure Fund and Cohen & Steers Co-Investment Partnership, L.P., which were variable interest entities as of December 31, 2016 and December 31, 2015, respectively.

[2] Pledged as collateral attributable to the consolidated balances of Cohen & Steers Active Commodities Strategy Fund, Inc. as of December 31, 2016 and December 31, 2015, respectively.

[3] Includes net income/(loss) attributable to redeemable noncontrolling interest for the periods presented.

[4] At December 31, 2016, there were no securities with unrealized losses continuously for a period of more than 12 months.

[5] At December 31, 2015, there were no securities with unrealized losses continuously for a period of more than 12 months.

[6] Includes other-than-temporary impairment charge of $2,846,000 related to the Company's seed investment in RAP.

[7] Amounts are included only for the time in which the investees were accounted for under the equity method.