Stock Based Compensation Fair Value Assumptions for Stock Options (Details) - Five Year Service Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Risk-free interest rate	1.42%	2.51%	2.72%
Expected volatility	29.15%	28.81%	32.01%
Expected term (in years)	5 years 7 months 6 days	5 years 10 months 24 days	5 years 8 months 12 days
Weighted average grant date fair value of options granted during the period	$ 12.65	$ 9.06	$ 11.31