Share-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-Based Compensation
Stock based compensation expense	$ 1.7	$ 1.3
Stock options
Assumptions used to determine value of the shares purchased under the stock purchase plan using Black-Scholes option pricing model
Expected annual dividend rate (as a percent)	1.32%
Risk-free interest rate (as a percent)	1.50%
Average expected life	5 years 9 months 18 days
Expected volatility of common stock (as a percent)	0.431%
Forfeiture rate (as a percent)	0.00%
Weighted average fair value of option grants (in dollars per share)	$ 4.47
Restricted Stock | Directors
Stock Compensation
Granted (in shares)	44,631
2010 Incentive Plan | Stock options
Stock Compensation
Granted (in shares)	231,394
2010 Incentive Plan | Restricted Stock
Stock Compensation
Granted (in shares)	290,914
Assumptions used to determine value of the shares purchased under the stock purchase plan using Black-Scholes option pricing model
Vesting period	3 years
Granted (in dollars per share)	$ 12.10