Overview (Details Textual) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 15, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash consideration receivable per share upon merger agreement		$ 6.80
Right to receive number of shares of common stock per share upon merger agreement		0.7275
Option change in control redemption premium, less than 90% cash transaction	101.00%
Accounting Standards Update 2018-02 [Member] | Accumulated Deficit [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results	$ 10.9
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			$ 100.0
Accounting Standards Update 2016-02 [Member] | Accumulated Deficit [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results	$ 0.2