Computation of Earnings per Share - Computation of Basic and Diluted Earnings Per Share (Parenthetical) (Details) (Stock Options, USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Options
Earnings Per Share Basic [Line Items]
Options to purchase shares that were not included in the respective computation of diluted EPS because their inclusion would have had an antidilutive effect	58,560	62,040	58,560	62,040
Options to purchase shares that were not included in the respective computation of diluted EPS because their inclusion would have had an antidilutive effect, weighted average exercise prices	$ 18.04	$ 17.95	$ 18.04	$ 17.95