CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, issued (in shares)	346,156	303,291
Preferred stock, outstanding (in shares)	346,156	303,291
Preferred stock, liquidation preference	$ 8,654	$ 7,582
Common Class A
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	30,345,646	28,140,721
Common stock, shares outstanding (in shares)	30,345,646	28,140,721