Stock-Based Compensation Plans (Details)	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Shares
Exercised (in shares)	(1,902)
2009 Plan | Employee and Directors Stock Options
Shares
Options outstanding at the beginning of the period (in shares)	14,408
Exercised (in shares)	(1,902)
Granted (in shares)	0
Forfeited (in shares)	0
Options outstanding at the end of the period (in shares)	12,506
Options exercisable (in shares)	12,506
Weighted average exercise price per share
Options outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 124.05
Exercised (in dollars per share) | $ / shares	89.17
Granted (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	0
Options outstanding at the end of the period (in dollars per share) | $ / shares	129.35
Options exercisable (in dollars per share) | $ / shares	$ 129.35