Stock-Based Compensation Plan (Details) (USD $)	3 Months Ended	12 Months Ended
	Jul. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2007
Stock Options Activity [Roll Forward]
Options outstanding at beginning of period (in shares)		1,192,680	972,680	930,180
Options outstanding at end of period (in shares)		1,335,680	1,192,680	972,680
Options exercisable at December 31, 2012 (in shares)		1,030,805
Expected to vest after December 31, 2012 (in shares)		304,875
Weighted Average Exercise Price [Roll Forward]
Outstanding at beginning of period (in dollars per share)		12.89	$ 10.32	$ 10.16
Outstanding at end of period (in dollars per share)		13.41	$ 12.89	$ 10.32
Exercisable at December 31, 2012 (in dollars per share)		12.07
Expected to vest after December 31, 2012 (in dollars per share)		17.96
Weighted Average Remaining Contractual Term [Abstract]
Weighted average remaining term of the stock options outstanding (in years)		6 years 4 months 24 days
Weighted average remaining term of the stock options exercisable (in years)		5 years 9 months 18 days
Weighted average remaining term of the stock options expected to vest (in years)		8 years 6 months
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value of options outstanding		11,920,000
Aggregate intrinsic value of options exercisable		10,403,000
Aggregate intrinsic value of options expected to vest		1,517,000
Closing stock price (in dollars per share)		21.95
Fair value of stock options		1,300,000	2,600,000	200,000
Fair value of stock options granted per share (in dollars per share)		8.36	$ 12.04	$ 5.18
Fair value assumptions and methodology [Abstract]
Stock price (in dollars per share)		17.77	$ 24.24	$ 13.97
Exercise price (in dollars per share)		17.77	$ 24.24	$ 13.97
Weighted average risk free interest rate (in hundredths)		0.75%	1.89%	1.77%
Dividend yield (in hundredths)		0.00%	0.00%	0.00%
Volatility factor (in hundredths)		50.00%	50.00%
Remaining volatility factor (in hundredths)		50.00%	50.00%
Remaining unamortized stock-based compensation cost		2,300,000
Stock-based compensation cost recognition period		2 years 6 months
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recorded		1,300,000	1,100,000	1,000,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recorded			$ 0	$ 100,000
Restricted Stock Grant [Abstract]
Restricted stock granted (in shares)					39,000
Vesting period of stock options (in years)		3 years
Vested shares to be issued annually (in hundredths)		33.333%
Restricted stock forfeited (in shares)	4,000
Restricted stock vested (in shares)	35,000
Payment of income tax withheld on vested restricted stock (in shares)				3,186
Directors [Member]
Stock Options Activity [Roll Forward]
Options granted (in shares)		40,000	40,000	42,500
Weighted Average Exercise Price [Roll Forward]
Granted (in dollars per share)		17.77	$ 21.62	$ 13.97
Fair value assumptions and methodology [Abstract]
Expected term		5 years 6 months	5 years 6 months	5 years 6 months
Volatility (in hundredths)		50.20%	50.80%	37.30%
Employees [Member]
Stock Options Activity [Roll Forward]
Options granted (in shares)		111,000	180,000
Options forfeited (in shares)		(8,000)
Weighted Average Exercise Price [Roll Forward]
Granted (in dollars per share)		17.77	$ 24.82
Forfeited (in dollars per share)		17.77
Fair value assumptions and methodology [Abstract]
Expected term		6 years 3 months	6 years 3 months
Volatility (in hundredths)		49.50%	50.10%