Share and Unit-based Plans - Stock Options Narrative (Details) - $ / shares		12 Months Ended
	May 30, 2017	Dec. 31, 2012	Dec. 31, 2017	Dec. 31, 2016	Jan. 06, 2016	Dec. 31, 2015	Dec. 09, 2015	Dec. 08, 2015	Dec. 31, 2014
Stock options
Share and unit-based plans
Grant date of award (in dollars per share)		$ 9.67
Volatility rate (as a percent)		25.85%
Dividend yield (as a percent)		3.69%
Risk free rate (as a percent)		1.20%
Current value (in dollars per share)		$ 59.57
Expected term (in years)		8 years
Stock options, outstanding, number (shares)			35,565	10,565	10,565	10,314	10,314	10,068	10,068
Stock options, outstanding, weighted average exercise price (in dollars per share)			$ 57.32	$ 56.77	$ 56.77	$ 58.15	$ 58.15	$ 59.57	$ 59.57
Non-qualified stock options
Share and unit-based plans
Volatility rate (as a percent)	30.19%
Dividend yield (as a percent)	4.93%
Risk free rate (as a percent)	2.08%
Expected term (in years)	8 years
Granted (shares)	25,000
Granted (in dollars per share)	$ 10.02
Share Price	$ 57.55