Share Based Compensation - Weighted Average and Assumptions (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average estimated fair value	$ 18.89	$ 18.48	$ 13.88
Quarterly dividend rate	$ 0.30	$ 0.29	$ 0.29
Expected term of stock appreciation rights, in years	4 years 8 months 6 days	4 years 8 months 15 days	4 years 3 months 19 days
Risk-free interest rate	0.70%	1.00%	1.60%
Dividend yield	2.60%	2.70%	3.40%
Expected stock price volatility	42.40%	43.30%	41.90%
Present value of dividends	$ 5.60	$ 5.37	$ 4.76