Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Accounting Policies [Abstract]
Net income attributable to common stockholders (Dilutive)	$ 8,359		$ 11,586		$ 32,339		$ 32,604
Stock options, SARs and restricted stock	243	[1]	442	[1]	355	[2]	446	[2]
Stock options, SARs and restricted stock (in usd per share)	$ (0.02)	[1]	$ (0.04)	[1]	$ (0.09)	[2]	$ (0.12)	[2]
Weighted Average Number of Shares Outstanding, Diluted	11,271		11,372		11,347		11,360
Diluted earnings per common share	$ 0.74		$ 1.02		$ 2.85		$ 2.87
Earnings Per Share, Basic [Abstract]
Net income attributable to common stockholders (Basic)	$ 8,359		$ 11,586		$ 32,339		$ 32,604
Weighted Average Number of Shares Outstanding, Basic	11,028		10,930		10,992		10,914
Basic earnings per common share	$ 0.76		$ 1.06		$ 2.94		$ 2.99

[1] For the three months ended September 30, 2015 and 2014, stock options and SARs of 476,699 and 118,583, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because they were anti-dilutive. For the three months ended September 30, 2015 and 2014, contingent shares of non-vested restricted stock of 45,034 and 42,514, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because performance conditions have not yet been met.

[2] For the nine months ended September 30, 2015 and 2014, stock options and SARs of 302,598 and 91,011, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because they were anti-dilutive. For the nine months ended September 30, 2015 and 2014, contingent shares of non-vested restricted stock of 40,194 and 38,874, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because performance conditions have not yet been met.