Stock Option Plans - Assumptions Used to Value Option Grants (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected life in years	5 years	5 years
Interest rate, minimum	0.70%	0.60%
Interest rate, maximum	1.45%	0.92%
Volatility, minimum	0.317%	0.327%
Volatility, maximum	0.328%	0.333%
Dividend yield	2.10% - 2.70%	2.50% - 2.70%