Related Party Transactions	12 Months Ended
Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company and its affiliated entities are the managing member, general partner and/or investment manager to the Company's investment management products and certain managed accounts. Management fees and incentive income are primarily earned from affiliated entities. As of December 31, 2017 and 2016, $13.5 million and $12.6 million, respectively, included in fees receivable are earned from related parties. The Company may, at its discretion, reimburse certain fees charged to the funds that it manages to avoid duplication of fees when such funds have an underlying investment in another affiliated investment fund. For the years ended December 31, 2017 and 2016, the Company reimbursed the funds it manages $0.1 million and $0.2 million, respectively, which were recorded net in management fees and incentive income in the accompanying consolidated statements of operation. For the year ended December 31, 2015, these amounts were immaterial. As of December 31, 2017, related amounts still payable were immaterial. As of December 31, 2016, related amounts still payable were $0.3 million and were reflected in fees payable in the accompanying consolidated statements of financial condition. Fees receivable and fees payable are recorded at carrying value, which approximates fair value. The Company may also make loans to employees or other affiliates, excluding executive officers of the Company. These loans are interest bearing and settle pursuant to the agreed-upon terms with such employees or affiliates and are included in due from related parties in the accompanying consolidated statements of financial condition. As of December 31, 2017 and 2016, loans to employees of $11.1 million and $9.2 million, respectively, were included in due from related parties on the accompanying consolidated statements of financial condition. Of these amounts $4.8 million and $3.3 million, respectively, are related to forgivable loans. These forgivable loans provide for a cash payment up-front to employees, with the amount due back to the Company forgiven over a vesting period. An employee that voluntarily ceases employment, or is terminated with cause, is generally required to pay back to the Company any unvested forgivable loans granted to them. The forgivable loans are recorded as an asset to the Company on the date of grant and payment, and then amortized to compensation expense on a straight-line basis over the vesting period. The vesting period on forgivable loans is generally one to three years. The Company recorded compensation expense of $2.1 million, $1.2 million, and $3.2 million for the years ended December 31, 2017, 2016, and 2015 respectively. This expense is included in employee compensation and benefits in the accompanying consolidated statement of operations. For the year ended December 31, 2017, the interest income was $0.1 million and for the years ended December 2016 and 2015, the interest income was insignificant for these related party loans and advances. This income is included in interest and dividends in the accompanying consolidated statement of operations. Included in due to related parties is approximately $0.6 million and $0.7 million as of December 31, 2017 and 2016, respectively, related to a subordination agreement with an investor in certain real estate funds. This total is based on a hypothetical liquidation of the real estate funds as of the balance sheet date. As of December 31, 2017 and 2016, included in due from related parties is $14.0 million and $18.7 million, respectively, related to the sales of portions of the Company's ownership interest in the activist business of Starboard Value to the Starboard principals. It is being financed through the profits of the relevant Starboard entities over a 5 year period and earns interest at 5% per annum. The interest income for the years ended December 31, 2017 and 2016, was $0.8 million and $0.6 million, respectively. The interest income for the year ended December 31, 2015 was immaterial. The remaining balance included in due from related parties of $9.7 million and $11.8 million as of December 31, 2017 and 2016, respectively, relates to amounts due to the Company from affiliated funds and real estate entities due to expenses paid on their behalf. Employees and certain other related parties invest on a discretionary basis within consolidated entities. These investments generally are subject to preferential management fee and performance fee arrangements. As of December 31, 2017 and 2016, such investments aggregated $28.2 million and $32.9 million, respectively, were included in redeemable non-controlling interests on the accompanying consolidated statements of financial condition. Their share of the net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds aggregated $7.2 million, $5.7 million, and $10.4 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Related Party Transactions

The Company and its affiliated entities are the managing member, general partner and/or investment manager to the Company's investment management products and certain managed accounts. Management fees and incentive income are primarily earned from affiliated entities. As of December 31, 2017 and 2016, $13.5 million and $12.6 million, respectively, included in fees receivable are earned from related parties. The Company may, at its discretion, reimburse certain fees charged to the funds that it manages to avoid duplication of fees when such funds have an underlying investment in another affiliated investment fund. For the years ended December 31, 2017 and 2016, the Company reimbursed the funds it manages $0.1 million and $0.2 million, respectively, which were recorded net in management fees and incentive income in the accompanying consolidated statements of operation. For the year ended December 31, 2015, these amounts were immaterial. As of December 31, 2017, related amounts still payable were immaterial. As of December 31, 2016, related amounts still payable were $0.3 million and were reflected in fees payable in the accompanying consolidated statements of financial condition. Fees receivable and fees payable are recorded at carrying value, which approximates fair value.

The Company may also make loans to employees or other affiliates, excluding executive officers of the Company. These loans are interest bearing and settle pursuant to the agreed-upon terms with such employees or affiliates and are included in due from related parties in the accompanying consolidated statements of financial condition. As of December 31, 2017 and 2016, loans to employees of $11.1 million and $9.2 million, respectively, were included in due from related parties on the accompanying consolidated statements of financial condition. Of these amounts $4.8 million and $3.3 million, respectively, are related to forgivable loans. These forgivable loans provide for a cash payment up-front to employees, with the amount due back to the Company forgiven over a vesting period. An employee that voluntarily ceases employment, or is terminated with cause, is generally required to pay back to the Company any unvested forgivable loans granted to them. The forgivable loans are recorded as an asset to the Company on the date of grant and payment, and then amortized to compensation expense on a straight-line basis over the vesting period. The vesting period on forgivable loans is generally one to three years. The Company recorded compensation expense of $2.1 million, $1.2 million, and $3.2 million for the years ended December 31, 2017, 2016, and 2015 respectively. This expense is included in employee compensation and benefits in the accompanying consolidated statement of operations. For the year ended December 31, 2017, the interest income was $0.1 million and for the years ended December 2016 and 2015, the interest income was insignificant for these related party loans and advances. This income is included in interest and dividends in the accompanying consolidated statement of operations.

Included in due to related parties is approximately $0.6 million and $0.7 million as of December 31, 2017 and 2016, respectively, related to a subordination agreement with an investor in certain real estate funds. This total is based on a hypothetical liquidation of the real estate funds as of the balance sheet date.

As of December 31, 2017 and 2016, included in due from related parties is $14.0 million and $18.7 million, respectively, related to the sales of portions of the Company's ownership interest in the activist business of Starboard Value to the Starboard principals. It is being financed through the profits of the relevant Starboard entities over a 5 year period and earns interest at 5% per annum. The interest income for the years ended December 31, 2017 and 2016, was $0.8 million and $0.6 million, respectively. The interest income for the year ended December 31, 2015 was immaterial.

The remaining balance included in due from related parties of $9.7 million and $11.8 million as of December 31, 2017 and 2016, respectively, relates to amounts due to the Company from affiliated funds and real estate entities due to expenses paid on their behalf.

Employees and certain other related parties invest on a discretionary basis within consolidated entities. These investments generally are subject to preferential management fee and performance fee arrangements. As of December 31, 2017 and 2016, such investments aggregated $28.2 million and $32.9 million, respectively, were included in redeemable non-controlling interests on the accompanying consolidated statements of financial condition. Their share of the net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds aggregated $7.2 million, $5.7 million, and $10.4 million for the years ended December 31, 2017, 2016, and 2015, respectively.