Equity	12 Months Ended
Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Equity	Note 10 — Equity In September 2017, the Company announced plans for a leveraged recapitalization, which included the authorization to repurchase up to $285 million of the Company’s common stock. In connection with the recapitalization, in October 2017 the Company borrowed $350 million under the Term Loan Facility and repaid $83.8 million outstanding under the previously existing bank loan facilities. See “Note 9 — Loan Facilities”. During the year ended December 31, 2018, the Company repurchased 7,497,635 shares of our common stock through a modified Dutch auction tender and open market transactions at an average price of $24.89 per share, for a total cost of $186.6 million. During the year ended December 31, 2017, the Company repurchased 3,777,548 common shares through a tender offer and other open market transactions at an average price of $17.41 per share, for a total cost of $65.8 million. In addition, the Company incurred fees and expenses relating to tender offers of $0.2 million and $0.7 million during the years ended December 31, 2018 and 2017, respectively. As of December 31, 2018, the Company has repurchased under the recapitalization plan 11,275,183 shares of its common stock at an average price of $22.39 per share for a total cost of $252.4 million and had $32.6 million remaining and authorized under its repurchase plan. In November 2017, the Company's Chairman, through an entity controlled by him, and the Company's Chief Executive Officer, in his personal capacity and through an entity controlled by him, each purchased $10.0 million of the Company’s common stock, for an aggregate total of $20.0 million, and a total of 1,159,420 common shares were issued. See “Note 8 — Related Parties”. In connection with the Acquisition, the Company issued 779,454 shares of common stock on the acquisition date, April 1, 2015. In addition, as a result of the Earnout being achieved for the period ending March 31, 2019, the Company will issue 334,048 shares of common stock after the Earnout period. The fair value of the contingent issuance of common shares was valued on the date of the Acquisition at $11.9 million and has been recorded as additional paid in capital in the consolidated statements of financial condition. As the Earnout was achieved, the par value of the shares will be transferred to common stock in the consolidated statement of financial condition when the Earnout shares are issued to the sellers of Cogent. See “Note 7 — Fair Value of Financial Instruments” and “Note 11 — Earnings per Share“. During 2018, 1,238,733 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 433,507 shares at an average price of $20.00 per share for a total cost of $8.7 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units. During 2017, 1,197,260 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 491,677 shares at an average price of $28.04 per share for a total cost of $13.8 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units. Dividends declared and paid on outstanding common share were $0.20, $1.40 and $1.80 for each of the years ended December 31, 2018, 2017 and 2016, respectively. In addition, dividend equivalent amounts are accrued and paid on outstanding restricted stock units and amounted to $1.1 million, $6.3 million and $8.5 million for the years ended December 31, 2018, 2017 and 2016, respectively, and paid amounts are included in dividends paid on the consolidated statements of cash flows. In the event a restricted stock unit holder’s employment is terminated, to the extent dividends have been paid to the holder, a portion of the dividend equivalent amount is required to be paid back (a “clawback”) to the Company and is netted against the dividend equivalent amounts herein. See “Note 13 — Deferred Compensation — Restricted Stock Units”.

Note 10 — Equity

In September 2017, the Company announced plans for a leveraged recapitalization, which included the authorization to repurchase up to $285 million of the Company’s common stock. In connection with the recapitalization, in October 2017 the Company borrowed $350 million under the Term Loan Facility and repaid $83.8 million outstanding under the previously existing bank loan facilities. See “Note 9 — Loan Facilities”.

During the year ended December 31, 2018, the Company repurchased 7,497,635 shares of our common stock through a modified Dutch auction tender and open market transactions at an average price of $24.89 per share, for a total cost of $186.6 million. During the year ended December 31, 2017, the Company repurchased 3,777,548 common shares through a tender offer and other open market transactions at an average price of $17.41 per share, for a total cost of $65.8 million. In addition, the Company incurred fees and expenses relating to tender offers of $0.2 million and $0.7 million during the years ended December 31, 2018 and 2017, respectively. As of December 31, 2018, the Company has repurchased under the recapitalization plan 11,275,183 shares of its common stock at an average price of $22.39 per share for a total cost of $252.4 million and had $32.6 million remaining and authorized under its repurchase plan.

In November 2017, the Company's Chairman, through an entity controlled by him, and the Company's Chief Executive Officer, in his personal capacity and through an entity controlled by him, each purchased $10.0 million of the Company’s common stock, for an aggregate total of $20.0 million, and a total of 1,159,420 common shares were issued. See “Note 8 — Related Parties”.

In connection with the Acquisition, the Company issued 779,454 shares of common stock on the acquisition date, April 1, 2015. In addition, as a result of the Earnout being achieved for the period ending March 31, 2019, the Company will issue 334,048 shares of common stock after the Earnout period. The fair value of the contingent issuance of common shares was valued on the date of the Acquisition at $11.9 million and has been recorded as additional paid in capital in the consolidated statements of financial condition. As the Earnout was achieved, the par value of the shares will be transferred to common stock in the consolidated statement of financial condition when the Earnout shares are issued to the sellers of Cogent. See “Note 7 — Fair Value of Financial Instruments” and “Note 11 — Earnings per Share“.

During 2018, 1,238,733 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 433,507 shares at an average price of $20.00 per share for a total cost of $8.7 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units.

During 2017, 1,197,260 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 491,677 shares at an average price of $28.04 per share for a total cost of $13.8 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units.

Dividends declared and paid on outstanding common share were $0.20, $1.40 and $1.80 for each of the years ended December 31, 2018, 2017 and 2016, respectively. In addition, dividend equivalent amounts are accrued and paid on outstanding restricted stock units and amounted to $1.1 million, $6.3 million and $8.5 million for the years ended December 31, 2018, 2017 and 2016, respectively, and paid amounts are included in dividends paid on the consolidated statements of cash flows. In the event a restricted stock unit holder’s employment is terminated, to the extent dividends have been paid to the holder, a portion of the dividend equivalent amount is required to be paid back (a “clawback”) to the Company and is netted against the dividend equivalent amounts herein. See “Note 13 — Deferred Compensation — Restricted Stock Units”.