Equity - Common Stock Continuous Offering Program (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 15, 2019	Sep. 19, 2016
Class of Stock [Line Items]
Other recoveries	$ (26,536,000)		$ 0	$ (26,536,000)	$ 0
Issuance of Common Stock, net	$ 14,534,000	$ 27,544,000
Common Stock [Member]
Class of Stock [Line Items]
Distribution agreement gross sales price (up to)						$ 750,000,000.0	$ 750,000,000.0
Continuous Equity Offering Program [Member] | Common Stock [Member]
Class of Stock [Line Items]
Issuance of Common Stock, net (shares)				5.0
Issuance of Common Stock, net				$ 42,500,000
Proceeds from issuance of common stock				$ 41,800,000
Continuous Equity Offering Program New [Member] | Common Stock [Member]
Class of Stock [Line Items]
Issuance of Common Stock, net (shares)				0.0
Weighted Average [Member] | Continuous Equity Offering Program [Member] | Common Stock [Member]
Class of Stock [Line Items]
Share price (in dollars per share)	$ 8.42			$ 8.42
Share price net of offering costs (in dollars per share)	$ 8.30			$ 8.30