Equity	9 Months Ended
Sep. 30, 2018
Stockholders' Equity Note [Abstract]
Equity	Equity On September 19, 2018, a dividend of $0.05 per share was paid to stockholders of record on September 5, 2018. For the nine months ended September 30, 2018, dividend payments of $0.15 per share were paid to stockholders and dividend equivalent payments of $0.8 million were paid to holders of restricted stock units. During the three months ended September 30, 2017, dividend payments of $0.45 per share were paid to stockholders and during the nine months ended September 30, 2017, dividend payments of $1.35 per share were paid to stockholders and dividend equivalent payments of $6.2 million were paid to holders of restricted stock units. In October 2017, the Company commenced a recapitalization plan to repurchase up to $285.0 million of its common stock. During the nine months ended September 30, 2018, the Company repurchased 6,810,797 common shares through a modified Dutch auction tender and open market transactions at an average price of $24.85, for a total cost of $169.2 million. During the nine months ended September 30, 2018, 1,145,849 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 428,798 shares at an average price of $19.97 per share for a total cost of $8.6 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units. During the nine months ended September 30, 2017, 1,095,224 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 448,738 shares at an average price of $29.06 per share for a total cost of $13.0 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units. In connection with the acquisition of Cogent, the Company issued 779,454 shares of common stock on the acquisition date, April 1, 2015. In addition, the Company agreed to issue 334,048 shares of common stock shortly after the second or fourth anniversary of the Acquisition if a revenue target was achieved. The revenue target was met in the quarter ended September 30, 2018 and the common stock related to the Earnout will be issued shortly after the fourth anniversary of the Acquisition. 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 condensed consolidated statements of financial condition. The par value of the shares will be transferred to common stock in the condensed consolidated statement of financial condition when the Earnout shares are issued to the sellers of Cogent. See "Note 4 "Fair Value of Financial Instruments" and "Note 8 - Earnings per Share".

Equity

On September 19, 2018, a dividend of $0.05 per share was paid to stockholders of record on September 5, 2018. For the nine months ended September 30, 2018, dividend payments of $0.15 per share were paid to stockholders and dividend equivalent payments of $0.8 million were paid to holders of restricted stock units. During the three months ended September 30, 2017, dividend payments of $0.45 per share were paid to stockholders and during the nine months ended September 30, 2017, dividend payments of $1.35 per share were paid to stockholders and dividend equivalent payments of $6.2 million were paid to holders of restricted stock units.

In October 2017, the Company commenced a recapitalization plan to repurchase up to $285.0 million of its common stock. During the nine months ended September 30, 2018, the Company repurchased 6,810,797 common shares through a modified Dutch auction tender and open market transactions at an average price of $24.85, for a total cost of $169.2 million.

During the nine months ended September 30, 2018, 1,145,849 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 428,798 shares at an average price of $19.97 per share for a total cost of $8.6 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units.

During the nine months ended September 30, 2017, 1,095,224 restricted stock units vested and were settled in shares of common stock, of which the Company is deemed to have repurchased 448,738 shares at an average price of $29.06 per share for a total cost of $13.0 million in conjunction with the payment of tax liabilities in respect of stock delivered to its employees in settlement of restricted stock units.

In connection with the acquisition of Cogent, the Company issued 779,454 shares of common stock on the acquisition date, April 1, 2015. In addition, the Company agreed to issue 334,048 shares of common stock shortly after the second or fourth anniversary of the Acquisition if a revenue target was achieved. The revenue target was met in the quarter ended September 30, 2018 and the common stock related to the Earnout will be issued shortly after the fourth anniversary of the Acquisition. 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 condensed consolidated statements of financial condition. The par value of the shares will be transferred to common stock in the condensed consolidated statement of financial condition when the Earnout shares are issued to the sellers of Cogent. See "Note 4 "Fair Value of Financial Instruments" and "Note 8 - Earnings per Share".