Stock Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2012

Stock-based Compensation Plans [Abstract]

Summary of the weighted average assumptions and results for options granted

	Year Ended December 31,
	2012			2011			2010
Assumptions:
Weighted average risk-free interest rate		0.99	%		2.11	%		2.22	%
Expected dividend yield		0.00	%		0.00	%		0.00	%
Expected volatility		62.70	%		59.37	%		56.43	%
Expected life of options		6.0 years			5.5 years			5.4 years
Weighted average fair value per share at date of grant	$	17.28		$	14.31		$	8.19

Summary of stock options and restricted stock rights for the Plans

A summary of stock options and restricted stock rights/units for the Plans is as follows:

	Stock Options									Restricted Stock Rights
	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value		Number of Shares			Weighted Average Grant- Date Fair Value
Outstanding at December 31, 2010		275,420			33.76		6.01		577,352		142,703			14.96
Options and stock rights granted		23,202			26.32						64,121			26.46
Options exercised/stock rights vested		(3,588	)		23.21						(44,255	)		26.73
Options expired		(36,885	)		48.17						—			—
Options and stock rights forfeited		(4,422	)		25.54						(6,221	)		23.96
Outstanding at December 31, 2011		253,727			31.27		5.95		1,058,206		156,348			18.97
Options and stock rights granted		285,510			22.28						72,038			27.97
Options exercised/stock rights vested		(6,090	)		13.68						(57,299	)		29.97
Options expired		(202,868	)		34.45						—			—
Options and stock rights forfeited		(76,963	)		24.19						(7,320	)		23.03
Outstanding at December 31, 2012		253,316		$	21.17		5.57	$	2,140,466		163,767		$	22.99
Exercisable at December 31, 2012		177,274		$	23.85		4.77	$	1,223,205		—		$	—