Stockholders' Equity and Redeemable Preferred Equity - Schedule of Dividend Declared (Details) - USD ($) $ / shares in Units, $ in Thousands									3 Months Ended				8 Months Ended	9 Months Ended
	Sep. 30, 2019	Aug. 01, 2019	Jul. 01, 2019	May 29, 2019	May 23, 2019	May 01, 2019	Mar. 05, 2019	Feb. 28, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Aug. 31, 2019	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Dividend per share (in dollars per share) | $ / shares						$ 0.330	$ 0.330					$ 0.33	$ 0.66		$ 0.33
Total Amount (in thousands)						$ 14,243	$ 14,218			$ 14,243	$ 14,218	$ 14,190		$ 28,500	$ 14,200
SMTA Preferred Shares
Class of Stock [Line Items]
Dividend per share (in dollars per share) | $ / shares			$ 0.625			$ 0.625	$ 0.625
Preferred stock dividends paid			$ 3,750			$ 3,750	$ 3,750		$ 3,800					$ 11,300
SubREIT Series A Preferred Stock
Class of Stock [Line Items]
Dividend per share (in dollars per share) | $ / shares		$ 45.000			$ 45.000			$ 45.000
Preferred stock dividends paid		$ 225			$ 225			$ 225
SubREIT Series B Preferred Stock
Class of Stock [Line Items]
Dividend per share (in dollars per share) | $ / shares	$ 30.330			$ 64.000
Preferred stock dividends paid	$ 4			$ 8