Stockholders' equity: (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders' equity:

Summary of the Company's quarterly dividends since the initial dividend payment

Dividend Period	Amount per Common Share		Record Date	Payment Date	Total Dividends Paid
Q3 2012	$	0.10	August 22, 2012	September 12, 2012	$	4,537
Q4 2012	$	0.11	November 21, 2012	December 12, 2012	$	5,012
Q1 2013	$	0.12	March 4, 2013	March 15, 2013	$	5,489
Q2 2013	$	0.13	May 31, 2013	June 18, 2013	$	6,145
Q3 2013	$	0.14	September 5, 2013	September 25, 2013	$	6,512
Q4 2013(1)	$	0.37	November 27, 2013	December 20, 2013	$	17,206
Q1 2014(1)	$	0.39	March 7, 2014	March 27, 2014	$	18,352
Q2 2014	$	0.17	May 30, 2014	June 18, 2014	$	7,882
Q3 2014	$	0.30	August 29, 2014	September 19, 2014	$	13,792
Q4 2014	$	0.31	November 26, 2014	December 12, 2014	$	14,190
Q1 2015(1)	$	0.35	March 11, 2015	March 26, 2015	$	16,001
Q2 2015(1)	$	0.42	May 22, 2015	June 12, 2015	$	18,972
Q3 2015	$	0.34	August 21, 2015	September 11, 2015	$	15,296
Q4 2015	$	0.35	November 20, 2015	December 11, 2015	$	16,045

Summary of the Company's amounts paid under the Capital Program

Dividend Period	Capital Program Amount(2)		Stock Buyback Amount During the Period		Stock Buyback Amount Greater than Capital Program Amount?	Payment Under Capital Program Paid As Dividend(1)		Amount Per Share Paid As Dividends Under the Capital Program
Q3 2013	$	10,000	$	—	No	$	—	$	—
Q4 2013	$	10,500	$	—	No	$	10,186	$	0.22
Q1 2014	$	10,500	$	14,196	Yes	$	10,707	$	0.23
Q2 2014	$	10,500	$	17,888	Yes	$	—	$	—
Q3 2014	$	12,000	$	15,943	Yes	$	—	$	—
Q4 2014	$	12,000	$	10,555	No	$	—	$	—
Q1 2015	$	12,000	$	8,119	No	$	1,357	$	0.03
Q2 2015	$	12,000	$	19,106	Yes	$	4,019	$	0.09
Q3 2015	$	12,000	$	12,169	Yes	$	—	$	—

(1)	Under the Capital Program if the amount spent on stock buybacks during a quarter is less than the program amount the difference is added to the dividend payment for the following quarter.
(2)	The indentures governing the Company's notes limit the Company's ability to return cash to its stockholders. Consequently, on November 2, 2015, the Company's Board of Directors suspended the $12.0 million quarterly minimum payment under the Capital Program. As the Company's cash flow increases the indenture covenants permit additional distributions to stockholders.