Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Abstract]
Net income attributable to common stockholders (Dilutive)	$ 16,364	$ 8,359	$ 38,687	$ 32,339
Stock options, SARs and restricted stock	176	243	291	355
Earnings Per Share, On Incremental Common Shares Attributable to Share-based Payment Arrangements	$ (0.02)	$ (0.02)	$ (0.10)	$ (0.09)
Weighted Average Number of Shares Outstanding, Diluted	10,649	11,271	10,755	11,347
Diluted earnings per common share	$ 1.54000	$ 0.74000	$ 3.6000	$ 2.85000
Earnings Per Share, Basic [Abstract]
Net Income (Loss) Available to Common Stockholders, Basic	$ 16,364	$ 8,359	$ 38,687	$ 32,339
Weighted Average Number of Shares Outstanding, Basic	10,473	11,028	10,464	10,992
Basic earnings per common share	$ 1.56	$ 0.76	$ 3.70	$ 2.94