Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	900,000,000	900,000,000
Common stock, shares issued (in shares)	43,805,741	43,795,073
Common stock, shares outstanding (in shares)	43,805,741	43,795,073
Series A Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	36,000,000	36,000,000
Preferred stock, shares issued (in shares)	1,460,245	1,566,386
Preferred stock, shares outstanding (in shares)	1,459,045	1,565,346
Preferred stock, liquidation preference per share (in usd per share)	$ 25.00	$ 25.00
Series A Cumulative Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	36,000,000	36,000,000
Preferred stock, shares issued (in shares)	2,154,248	1,287,169
Preferred stock, shares outstanding (in shares)	2,142,676	1,281,804
Preferred stock, liquidation preference per share (in usd per share)	$ 25.00	$ 25.00
Series L Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	9,000,000	9,000,000
Preferred stock, shares issued (in shares)	8,080,740	8,080,740
Preferred stock, shares outstanding (in shares)	8,080,740	8,080,740
Preferred stock, liquidation preference per share (in usd per share)	$ 28.37	$ 28.37