Share Based Compensation - Weighted Average and Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Weighted-average estimated fair value	$ 22.50	$ 22.23	$ 21.87
Quarterly dividend rate	$ 0.48	$ 0.46	$ 0.44
Expected term of stock options, in years	4 years 2 months 12 days	4 years 2 months 12 days	4 years 6 months
Risk-free interest rate	1.30%	2.50%	2.40%
Dividend yield	2.50%	2.60%	2.50%
Expected stock price volatility	28.50%	28.90%	27.90%
Present value of dividends	$ 7.89	$ 7.29	$ 7.51