Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 plan	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2005
Stock-Based Compensation
Number of stock-based compensation plans	1
Number of shares reserved under the plan					735,000
Number of additional shares authorized under the plan				700,000
Number of shares available for future awards	513,026,000
Stock-based compensation
Stock-based compensation expense before income taxes	$ 1,940,000	$ 1,481,000	$ 1,165,000
Deferred tax benefit	679,000	518,000	408,000
Reduction of net income	1,261,000	963,000	757,000
Unrecognized stock-based compensation expense	3,132,000
Period of recognition of stock-based compensation expense	5 years
Amount received from exercise of options	$ 2,435,000	$ 937,000	$ 692,000
Options and stock appreciation rights (SARs)
Stock-based compensation
Award vesting limit per year (as a percent)	20.00%
Period after grant date after which the award expires	10 years
Assumptions used in SAR/Option valuations
Dividend yield (as a percent)	2.80%	2.52%	2.48%
Expected volatility (as a percent)	22.54%	22.04%	22.64%
Risk free interest rate (as a percent)	1.26%	1.44%	2.90%
Forfeitures (as a percent)	6.40%	4.20%	6.07%
Expected life of awards	6 years 7 months 6 days	7 years 7 months 6 days	7 years 6 months
Restricted stock | Minimum
Stock-based compensation
Award vesting period	3 years
Restricted stock | Maximum
Stock-based compensation
Award vesting period	5 years
Restricted stock units (RSUs) | Executive Officer
Stock-Based Compensation
Number of shares available for future awards	28,579,000	22,668,000	16,857,000
Stock-based compensation
Award vesting period	3 years	3 years	3 years