Earnings Per Share (Details) - USD ($) $ / shares in Units, $ 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, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net Earnings	$ 13,196	$ (951)	$ 14,817	$ 5,026	$ 17,541	$ 11,792	$ 15,523	$ 5,795	$ 32,088	$ 50,651	$ 40,231
Basic - Weighted Average Shares Outstanding									18,015,151	18,217,384	18,297,371
Effect of dilutive securities									478,296	523,474	536,082
Diluted - Weighted Average Shares Outstanding									18,493,447	18,740,858	18,833,453
Basic Earnings per Share	$ 0.74	$ (0.05)	$ 0.81	$ 0.27	$ 0.96	$ 0.65	$ 0.85	$ 0.32	$ 1.78	$ 2.78	$ 2.20
Diluted Earnings per Share	$ 0.73	$ (0.05)	$ 0.79	$ 0.27	$ 0.93	$ 0.63	$ 0.83	$ 0.31	$ 1.74	$ 2.70	$ 2.14
Anti-dilutive securities excluded from earnings per share calculation (in shares)									222,092	91,199	132,803