Quarterly Consolidated Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Consolidated Financial Information (Unaudited)
Total revenue	$ 55,195	$ 57,758	$ 43,843	$ 42,814	$ 41,563	$ 45,519	$ 43,865	$ 43,340	$ 47,203	$ 37,952	$ 37,953	$ 35,304	$ 199,610	$ 174,287	$ 158,412
Net income	$ 2,973	$ 2,577	$ (492)	$ 2,298	$ (277)	$ 979	$ 2,214	$ 4,331	$ 6,553	$ (2,229)	$ 9,692	$ 1,610	$ 7,356	$ 7,247	$ 15,626
Basic earnings (loss) per common share (in dollars per share)	$ 0.38	$ 0.33	$ (0.06)	$ 0.29	$ (0.03)	$ 0.12	$ 0.28	$ 0.55	$ 0.84	$ (0.29)	$ 1.20	$ 0.20	$ 0.94	$ 0.92	$ 1.95
Diluted earnings (loss) per common share (in dollars per share)	$ 0.37	$ 0.32	$ (0.06)	$ 0.29	$ (0.03)	$ 0.12	$ 0.27	$ 0.53	$ 0.81	$ (0.28)	$ 1.17	$ 0.19	$ 0.92	$ 0.89	$ 1.89
Average common shares outstanding (in shares)	7,739	7,839	7,841	7,848	7,839	7,938	7,976	7,914	7,846	8,126	8,106	8,033	7,811	7,917	8,029
Diluted average common shares outstanding (in shares)	7,872	7,963	7,991	8,044	8,037	8,123	8,179	8,129	8,084	8,329	8,303	8,273	7,982	8,141	8,289