Stock-Based Compensation - Summary of Restricted Stock, Stock Grants, Stock Units and Performance Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock Units, Stock Grants, and Stock Units
Stocks granted and the weighted average fair value
Units granted (in shares)	132,997	161,963	141,811
Grant date fair value (in dollars per share)	$ 77.51	$ 72.60	$ 67.34
Number of granted awards to be settled in cash (in shares)	66,252	67,599	43,952
Performance Shares
Stocks granted and the weighted average fair value
Units granted (in shares)	171,708	147,706	166,666
Grant date fair value (in dollars per share)	$ 76.56	$ 78.99	$ 66.60