Accounting Policies - Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Earnings Per Share, Basic [Abstract]
Net income attributable to common stockholders	$ 27,745		$ (4,291)		$ 43,935		$ 17,912
Weighted Average Number of Shares Outstanding, Basic	10,815		10,468		10,776		10,417
Basic earnings per common share (dollars per share)	$ 2.57		$ (0.41)		$ 4.08		$ 1.72
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted-average shares, dilutive securities, stock options, SARs, and restricted stock (shares)	383	[1]	0	[1]	403	[2]	545	[2]
Earnings Per Share, On Incremental Common Shares Attributable to Share-based Payment Arrangements	$ (0.09)	[1]	$ 0.00	[1]	$ (0.15)	[2]	$ (0.09)	[2]
Net Income (Loss) Available to Common Stockholders, Diluted	$ 27,745		$ (4,291)		$ 43,935		$ 17,912
Weighted-average shares, diluted (shares)	11,198		10,468		11,179		10,962
Diluted Earnings per common share	$ 2.48		$ (0.41)		$ 3.93		$ 1.63

[1] For the three months ended June 30, 2013 and 2012, stock options and SARs of 89,937 and 1,270,777, 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 June 30, 2013 and 2012, contingent shares of non-vested restricted stock of 44,894 and 146,311, 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 six months ended June 30, 2013 and 2012, stock options and SARs of 46,969 and 469,577, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because they were anti-dilutive. For the six months ended June 30, 2013 and 2012, contingent shares of non-vested restricted stock of 35,097 and 92,800, respectively, were outstanding but not included in the computation of diluted earnings per share of common stock because performance conditions were not met.