Stock-based compensation plans (Tables)

12 Months Ended

Dec. 31, 2012

Equity [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The Company used the Black-Scholes option-pricing model with the following weighted-average assumptions to value options granted in 2012:

	2012		2010
Dividend yield		0.0%		0.0	%
Expected volatility		85.0%		78.1%
Risk-free interest rate		1.4%		3.1%
Expected option lives		6 years		8 years

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

The following table presents the activity related to options under all plans for the years ended December 31, 2012, 2011, and 2010.

	2012					2011					2010
	Options outstanding			Weighted- average exercise price		Options outstanding			Weighted- average exercise price		Options outstanding			Weighted- average exercise price
Balance at beginning of year		144,370		$	68.90		156,522		$	68.26		99,062		$	121.80
Granted		32,399			4.77		—			—		77,075			5.71
Cancelled/forfeited		(29,213	)		71.78		(5,715	)		74.78		(19,615	)		92.49
Expired		(8,110	)		68.97		(6,437	)		48.00		—			—
Balance at end of year		139,446		$	53.39		144,370		$	68.90		156,522		$	68.26
Exercisable at end of year		50,997					73,345					54,806

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Remaining Contractual Term [Table Text Block]

Information regarding the number, weighted-average exercise price, and weighted-average remaining contractual life of options by range of exercise price at December 31, 2012 is as follows:

	Options outstanding						Exercisable options
Exercise price range	Number of options		Weighted- average exercise price		Weighted- average remaining contractual life (years)		Number of options		Weighted- average exercise price
Under $50.00		88,449	$	5.37		8.0		—	$	—
$50.01 – $80.00		—		0.00		0.0		—		—
$80.01 – $120.00		30,326		97.53		3.3		30,326		97.53
$120.01 – $160.00		10,468		134.61		1.3		10,468		134.61
$160.01 – $220.00		2,470		207.49		3.1		2,470		207.49
$220.01 – $279.00		7,733		270.45		4.1		7,733		270.45
		139,446	$	53.39		6.2		50,997	$	136.69

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

The following table presents the activity for nonvested restricted stock for the year ended December 31, 2012:

	Number of shares			Weighted- average grant date fair value per share
Nonvested as of December 31, 2011		138,864		$	15.72
Granted		65,232			5.67
Cancelled/Forfeited		(21,697	)		7.04
Exercised/Released		(25,208	)		7.20
Nonvested as of December 31, 2012		157,191		$	14.11