Stockholders’ Equity - Dividend Rights (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) Vote / shares	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Offering Costs
Offering costs	$ 1,949,000	$ 1,072,000
Deferred Offering Costs			$ 21,000
Common Stock
Dividends Rights
No dividends declared	0
Voting Rights
No dividends declared	$ 0
Common stock, vote per share | Vote / shares	1