Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Basic EPS:
Net Income (Loss)	$ 74,615	$ 71,971
Income, Share Amounts	11,655	11,453
Earnings (Loss) Per Share, Basic	$ 6.40	$ 6.28
Dilutive Securities:
Dilutive Restricted Stock Unit Awards	94	6
Dilutive Stock Option Awards	15	55
Diluted EPS:
Net Income (Loss) Available to Common Stockholders, Diluted	$ 74,615	$ 71,971
Weighted Average Number of Shares Outstanding, Diluted	11,764	11,514
Earnings (Loss) Per Share, Diluted	$ 6.34	$ 6.25
Stock Options [Member]
Earnings Per Share (Textual) [Abstract]
Antidilutive shares not included in the computation of diluted EPS	600	300
Restricted Stock Units (RSUs) [Member]
Earnings Per Share (Textual) [Abstract]
Antidilutive shares not included in the computation of diluted EPS	100	100
Performance Shares [Member]
Earnings Per Share (Textual) [Abstract]
Antidilutive shares not included in the computation of diluted EPS	100
Warrant [Member]
Earnings Per Share (Textual) [Abstract]
Antidilutive shares not included in the computation of diluted EPS	4,300	4,300