Accounting Policies - Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Accounting Policies [Abstract]
Net income attributable to common stockholders (Basic)	$ 11,586		$ 15,413		$ 32,604		$ 59,348
Net income attributable to common stockholders (Dilutive)	$ 11,586		$ 15,413		$ 32,604		$ 59,348
Earnings Per Share, Basic [Abstract]
Stock options, SARs and restricted stock	442	[1]	370	[1]	446	[2]	392	[2]
Stock options, SARs and restricted stock (in usd per share)	$ (0.04)	[1]	$ (0.05)	[1]	$ (0.12)	[2]	$ (0.20)	[2]
Weighted Average Number of Shares Outstanding, Basic	10,930		10,843		10,914		10,799
Basic earnings per common share	$ 1.06		$ 1.42		$ 2.99		$ 5.50
Weighted Average Number of Shares Outstanding, Diluted	11,372		11,213		11,360		11,191
Diluted earnings per common share	$ 1.02		$ 1.37		$ 2.87		$ 5.3

[1] For the three months ended September 30, 2014 and 2013, stock options and SARs of 118,583 and 36,983, 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, 2014 and 2013, contingent shares of non-vested restricted stock of 42,514 and 44,894, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because performance conditions were not met.

[2] For the nine months ended September 30, 2014 and 2013, stock options and SARs of 91,011 and 43,640, 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, 2014 and 2013, contingent shares of non-vested restricted stock of 38,874 and 38,363, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because performance conditions were not met.