Stock-Based Compensation Plan (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Aggregate Intrinsic Value [Abstract]
Closing stock price (in dollars per share)	$ 23.57		$ 23.57
Fair value assumptions and methodology [Abstract]
Stock price (in dollars per share)	$ 26.41	$ 17.77	$ 26.41	$ 17.77
Exercise price (in dollars per share)	$ 26.41	$ 17.77	$ 26.41	$ 17.77
Dividend yield (in hundredths)			0.00%	0.00%
Volatility factor (in hundredths)			50.00%
Remaining volatility factor (in hundredths)			50.00%
Directors [Member]
Fair value assumptions and methodology [Abstract]
Expected term			5 years 6 months	5 years 6 months
Volatility (in hundredths)			58.60%	50.20%
Weighted average risk free interest rate (in hundredths)			1.16%	0.75%
Employees [Member]
Fair value assumptions and methodology [Abstract]
Expected term			6 years 3 months	6 years 3 months
Volatility (in hundredths)			56.70%	49.50%
Weighted average risk free interest rate (in hundredths)			1.35%	0.75%
Stock Options [Member]
Stock Options Activity [Roll Forward]
Options outstanding at beginning of period (in shares)			1,335,680	1,192,680
Options outstanding at end of period (in shares)	1,327,485	1,343,680	1,327,485	1,343,680
Options exercisable at end of period (in shares)	1,075,810	952,055	1,075,810	952,055
Weighted Average Exercise Price [Roll Forward]
Outstanding at beginning of period (in dollars per share)			$ 13.41	$ 12.89
Outstanding at end of period (in dollars per share)	$ 14.43	$ 13.44	$ 14.43	$ 13.44
Exercisable at end of period (in dollars per share)	$ 12.37	$ 12.15	$ 12.37	$ 12.15
Weighted Average Remaining Contractual Term [Abstract]
Weighted average remaining term of the stock options exercisable (in years)			5 years 8 months 12 days	6 years 2 months 12 days
Stock-based compensation expense recorded	$ 0.4	$ 0.3	$ 0.7	$ 0.6
Remaining unamortized stock-based compensation cost	2.4		2.4
Stock-based compensation cost recognition period			2 years 8 months 12 days
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value of options exercised	1.5		1.5
Aggregate intrinsic value of options outstanding	12.6		12.6
Stock Options [Member] | Directors [Member]
Stock Options Activity [Roll Forward]
Options granted - directors and employees (in shares)			40,000	40,000
Weighted Average Exercise Price [Roll Forward]
Granted - directors and employees (in dollars per share)			$ 26.41	$ 17.77
Weighted Average Remaining Contractual Term [Abstract]
Vesting period of stock options (in years)			1 year
Remaining unamortized stock-based compensation cost	0.5		0.5
Stock-based compensation cost recognition period			1 year
Restricted Stock Grant [Abstract]
Vesting period of stock options (in years)			1 year
Stock Options [Member] | Employees [Member]
Stock Options Activity [Roll Forward]
Options granted - directors and employees (in shares)			51,300	111,000
Options forfeited - employees (in shares)			(834)	0
Options exercised - employees (in shares)			(98,661)	0
Weighted Average Exercise Price [Roll Forward]
Granted - directors and employees (in dollars per share)			$ 26.41	$ 17.77
Forfeited - employees (in dollars per share)			$ 5.60
Options exercised - employees (in dollars per share)			$ 11.80
Weighted Average Remaining Contractual Term [Abstract]
Vesting period of stock options (in years)			4 years
Percentage of stock options vesting after one year (in hundredths)			25.00%
Percentage of stock options vesting each month following first year (in hundredths)			2.083%
Restricted Stock Grant [Abstract]
Vesting period of stock options (in years)			4 years
Restricted Stock [Member]
Weighted Average Remaining Contractual Term [Abstract]
Vesting period of stock options (in years)			4 years
Stock-based compensation expense recorded	0.1		0.1
Remaining unamortized stock-based compensation cost	0.7		0.7
Stock-based compensation cost recognition period			3 years 10 months 24 days
Restricted Stock Grant [Abstract]
Restricted stock granted (in shares)			28,150
Restricted common stock value			$ 0.7
Vesting period of stock options (in years)			4 years