Equity Transactions, Sale of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended		18 Months Ended
	Jun. 30, 2019	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2018
Class of Stock [Line Items]
Common stock issued	3,737,500	400,000,000	280,502	1,008,699		398,516	458,541	321,800
Weighted average sales price		$ 85.01	$ 76.47		$ 100.19			$ 93.33	$ 92.98
Net proceeds (in millions)		$ 33.6	$ 21.2	$ 92.6		$ 39.4		$ 29.7	$ 163.8
Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)							180,277
Conversion of Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)					485,629	20,608
Conversion of Common OP Units [Member] | Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued					1.0000
Conversion of Common OP Units to common stock (in shares)					485,629
Series A-1 Preferred OP Units [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)					22,707	13,430
Series A-1 Preferred OP Units [Member] | Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued					2.4390
Conversion of Common OP Units to common stock (in shares)					55,370	32,752
Series A-4 Preferred Op Units [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)					4,708	13,765
Series A-4 Preferred Op Units [Member] | Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued					0.4444
Conversion of Common OP Units to common stock (in shares)					2,092	6,116
Series A-4 Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)					1,062,789	22,576
Series A-4 Preferred Stock [Member] | Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued					0.4444
Conversion of Common OP Units to common stock (in shares)					472,366	10,033
Series C preferred OP units [Member]
Class of Stock [Line Items]
Conversion of Common OP Units to common stock (in shares)					4,014	1,919
Series C preferred OP units [Member] | Common OP Units [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued					1.1100
Conversion of Common OP Units to common stock (in shares)					4,455	2,130