Share-based Compensation by Share-based Payment Award, Initial Contractual Term

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Amount of commitment made to pay deferred cash remuneration.

+ References

No definition available.

+ Details

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
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- Definition

Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
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Share-Based Compensation and Employee Ownership Plans Narrative (Details) $ in Millions		12 Months Ended
	Dec. 05, 2016	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio	0.25
Equity Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under compensation plan, in shares \| shares		0
Stock-compensation expense recognized in connection with compensation plan		$ 28.4	$ 26.0	$ 21.7
Tax benefit of stock-compensation expense recognized in connection with compensation plan		$ 7.7	$ 11.4	$ 5.0
Equity Plans \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, initial term		7 years
Equity Plans \| Employee Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period		2 years
Equity Plans \| Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period		5 years
Equity Plans \| Restricted Shares and Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		$ 56.4
Vested, shares \| shares		2,036,366	1,487,092
Equity Plans \| Restricted Stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period		2 years
Equity Plans \| Restricted Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period		5 years
Equity Plans \| Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SAR's, initial term		5 years
Unrecognized compensation expense			$ 0.1
Vested, shares \| shares		25,000	0
Deferred Cash Award \| Cowen Group, Inc. 2010 Equity and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred cash awards granted		$ 24.1
Stock compensation award, vesting period		4 years
Convergex Group [Member] \| Deferred Cash Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred cash awards granted		$ 2.4