Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation These unaudited Condensed Consolidated Financial Statements reflect the historical balance sheets, statements of operations and of comprehensive income, statements of changes in stockholders’ equity and statements of cash flows of the Company. Within these Condensed Consolidated Financial Statements, OM plc, HNA, Paulson and their related entities, as defined above, are referred to as “related parties.” The Condensed Consolidated Financial Statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). In the opinion of management, all normal and recurring adjustments considered necessary for a fair presentation of the Company’s Condensed Consolidated Financial Statements have been included. All dollar amounts, except per-share data in the text and tables herein, are stated in millions unless otherwise indicated. Transactions between the Company and its related parties are included in the Condensed Consolidated Financial Statements, however, material intercompany balances and transactions among the Company, its consolidated Affiliates and consolidated Funds are eliminated in consolidation. As a result of the Redomestication on July 12, 2019, discussed in Note 1, the Company revised its equity accounts to reflect a U.S. domiciled company presentation on the Condensed Consolidated Statements of Changes in Stockholders’ equity and the Condensed Consolidated Balance Sheets for all periods presented. The previously issued ordinary shares of BrightSphere Investment Group plc were exchanged on a one-for-one basis for newly issued shares of common stock of BrightSphere Investment Group Inc. The Redomestication and related internal reorganization was accounted for consistent with a reorganization of entities under common control in accordance with ASC 805 Business Combinations. Accordingly, the transfer of the assets and liabilities and exchange of shares was recorded in the new entity (BrightSphere Investment Group Inc.) at their carrying amounts from the transferring entity (BrightSphere Investment Group plc) at the date of transfer. Certain disclosures included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (annual report on Form 10-K) are not required to be included on an interim basis in the Company’s quarterly reports on Form 10-Q. The Company has condensed or omitted these disclosures. These unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K as filed with the Securities and Exchange Commission (“SEC”) on March 2, 2020. The Company’s significant accounting policies, which have been consistently applied, are summarized in those financial statements.
Use of estimates	Use of estimatesThe preparation of these Condensed Consolidated Financial Statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. The three and six months ended June 30, 2020 were characterized by heightened uncertainty due to the COVID-19 pandemic which could impact estimates and assumptions made by management. Actual results could differ from such estimates, and the differences may be material to the Condensed Consolidated Financial Statements.
Recently adopted accounting standards	Recently adopted accounting standards In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820). This standard modifies the disclosure requirements on fair value measurements and is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company adopted the standard on January 1, 2020. Notably, this guidance removes the disclosure requirements for the valuation processes for Level III fair value measurements. This guidance also adds new disclosure requirements for the range and weighted average of significant unobservable inputs used to develop fair value measurements categorized within Level III of the fair value hierarchy. The Company has determined that the adoption of this standard did not have a material impact on its Condensed Consolidated Financial Statements and related disclosures. New accounting standards not yet adopted The Company has considered all other newly issued accounting guidance that is applicable to the Company’s operations and the preparation of the unaudited Condensed Consolidated Financial Statements, including those that have not yet been adopted. The Company does not believe that any such guidance has or will have a material effect on its Condensed Consolidated Financial Statements and related disclosures.