Stockholders' equity:

12 Months Ended

Dec. 31, 2017

Stockholders' equity:

Stockholders' equity:

7. Stockholders' equity:

Authorized shares

        The Company has 75.0 million shares of authorized $0.001 par value common stock and 10,000 authorized but unissued shares of $0.001 par value preferred stock. The holders of common stock are entitled to one vote per common share and, subject to any rights of any series of preferred stock, dividends may be declared and paid on the common stock when determined by the Company's Board of Directors.

Common stock buybacks

        The Company's Board of Directors has approved $50.0 million for purchases of the Company's common stock under a buyback program (the "Buyback Program"). At December 31, 2017, there was $41.5 million remaining for purchases under the Buyback Program. During 2017, 2016 and 2015, the Company purchased approximately 0.1 million, 0.1 million and 1.2 million shares of its common stock for $1.8 million, $4.5 million and $39.4 million, respectively. These common shares were subsequently retired.

Dividends on common stock

        Dividends are recorded as a reduction to retained earnings. Dividends on unvested restricted shares of common stock are paid as the awards vest. The Company's initial quarterly dividend payment was made in the third quarter of 2012.

        The payment of any future dividends and any other returns of capital, including stock buybacks, will be at the discretion of the Company's Board of Directors and may be reduced, eliminated or increased and will be dependent upon the Company's financial position, results of operations, available cash, cash flow, capital requirements, limitations under the Company's debt indentures and other factors deemed relevant by the Company's Board of Directors. The Company is a Delaware Corporation and under the General Corporate Law of the State of Delaware distributions may be restricted including a restriction that distributions, including stock purchases and dividends, do not result in an impairment of a corporation's capital, as defined under Delaware Law. The indentures governing the Company's notes limit the Company's ability to return cash to its stockholders.