Equity Based Compensation Plans - Restricted Stock Activity and LITP Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock
Total Unvested Units
Unvested at beginning of year (in shares)	114,877	91,058	90,823	58,349
Granted (in shares)	41,643	51,945	62,706
Vested (in shares)	(13,222)	(48,212)	(29,675)
Forfeited and canceled (in shares)	(4,602)	(3,498)	(557)
Unvested at end of year (in shares)	114,877	91,058	90,823	58,349
Weighted- average grant price
Unvested at beginning of year (in dollars per share)	$ 180.99	$ 163.49	$ 149.11
Granted (in dollars per share)	235.93	194.70	177.28
Vested (in dollars per share)	143.56	150.76	170.17
Forfeited and canceled (in dollars per share)	158.06	158.71	119.37
Unvested at end of year (in dollars per share)	$ 197.62	$ 180.99	$ 163.49	$ 149.11
Long Term Incentive Plans - Z Units and 2014 LTIP Units
Total Unvested Units
Unvested at beginning of year (in shares)	1,890	11,161	23,212	60,027
Granted (in shares)	0	0	0
Vested (in shares)	(9,176)	(12,051)	(32,961)
Converted (in shares)	0	0	0
Forfeited and canceled (in shares)	(95)	0	(3,854)
Unvested at end of year (in shares)	1,890	11,161	23,212	60,027
Weighted- average grant price
Unvested at beginning of year (in dollars per share)	$ 75.03	$ 75.03	$ 75.11
Unvested at end of year (in dollars per share)	$ 75.03	$ 75.03	$ 75.03	$ 75.11
Total Vested Units
Vested, beginning balance (in shares)	134,081	213,300	181,027
Vested, units granted (in shares)	0	0	0
Vested, units vested (in shares)	9,176	12,051	32,961
Converted (in shares)	0	(91,270)	(688)
Cancelled (in shares)	0	0	0
Vested, ending balance (in shares)	143,257	134,081	213,300	181,027
Total Outstanding Units
Total outstanding units, beginning balance (in shares)	145,242	236,512	241,054
Total outstanding units, granted (in shares)	0	0	0
Total outstanding units, vested (in shares)	0	0	0
Total outstanding units, converted (in shares)	0	(91,270)	(688)
Total outstanding units, cancelled (in shares)	(95)	0	(3,854)
Total outstanding units, ending balance (in shares)	145,147	145,242	236,512	241,054
Weighted- average Remaining Contractual Life (years)	5 years 2 months 12 days	6 years 6 months	7 years 6 months	8 years 6 months