Share and Unit-based Plans - Stock Option Activity (Details) - Stock options - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Options
Balance at beginning of year (shares)	35,565	10,565	10,314
Granted (shares)	0	25,000	0
Exercised (in shares)	0	0	0
Special dividend adjustment (shares)	0	0	251
Balance at end of year (shares)	35,565	35,565	10,565
Weighted Average Exercise Price (in dollars per share)
Balance at beginning of year (in dollars per share)	$ 57.32	$ 56.77	$ 58.15
Granted (in dollars per share)	0.00	57.55	0.00
Exercised (in dollars per share)	0.00	0.00	0.00
Special dividend adjustment (in dollars per share)	0.00	0.00	56.77
Balance at end of year (in dollars per share)	$ 57.32	$ 57.32	$ 56.77