Equity-based Compensation - Schedule of Grant Date Fair Value (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	2,070,000	6,900,000
Weighed average fair value (in dollars per share)	$ 2.48	$ 1.69
Brightsphere Equity Incentive Plan \| Restricted shares (RSA)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	18,000	304,389	342,637
Granted during the year (in dollars per share)	$ 10.09	$ 15.84	$ 15.13
Brightsphere Equity Incentive Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	88,980	48,930	51,779
Granted during the year (in dollars per share)	$ 12.4	$ 14.98	$ 14.45
Brightsphere Equity Incentive Plan \| Performance-based RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	0	83,092	175,586
Granted during the year (in dollars per share)	$ 0	$ 9.78	$ 10.26
Brightsphere Equity Incentive Plan \| Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	9,013	0	0
Granted during the year (in dollars per share)	$ 14.62	$ 0	$ 0
Brightsphere Equity Incentive Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	2,070,000	6,900,000	0
Weighed average fair value (in dollars per share)	$ 2.48	$ 1.69	$ 0

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Net number of non-option equity instruments granted to participants.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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