Stock Purchase (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2012	Dec. 31, 2017	Jun. 26, 2017	Jan. 01, 2017	Dec. 31, 2013
Class of Warrant or Right [Line Items]
Value of warrants		$ 5.9
Value of common stock		$ 8.5
$1.03 Warrant
Class of Warrant or Right [Line Items]
Price per share (dollars per share)		$ 1.03
Stock and warrants purchase price		$ 14.4
Shares of common stock (shares)		14,000,000.0
Exercise price (dollars per share)		$ 1.03				$ 1.03
$2.00 Warrant
Class of Warrant or Right [Line Items]
Warrants to purchase common stock (shares)		7,000,000.0
Exercise price (dollars per share)		$ 2.00
Additional warrant to purchase common stock (shares)		7,000,000.0
Additional exercised warrant per purchase agreement (shares)			370,307
Proceeds from warrants	$ 0.7
Unexercised warrants (shares)				45,564	415,871