Quarterly report pursuant to Section 13 or 15(d)

Subsequent Events Subsequent Events (Details)

v3.19.1
Subsequent Events Subsequent Events (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended
May 03, 2019
Mar. 31, 2019
Dec. 31, 2018
May 09, 2019
May 06, 2019
Subsequent Event [Line Items]          
Payments for Key-Man Penalties   $ 2.0 $ 2.0    
Common stock, authorized (in shares)   50,000,000 50,000,000    
Subsequent Event          
Subsequent Event [Line Items]          
Options to purchase shares of common stock (in shares) 173,000        
Price per share, common stock options available (in usd per share) $ 2.48        
Minimum | Subsequent Event          
Subsequent Event [Line Items]          
Common stock, authorized (in shares)       50,000,000  
Maximum | Subsequent Event          
Subsequent Event [Line Items]          
Common stock, authorized (in shares)       100,000,000  
Johnson Controls Agreement | Johnson Controls          
Subsequent Event [Line Items]          
Shares of common stock issued (in shares)   807,436      
Johnson Controls Agreement | Johnson Controls | Subsequent Event          
Subsequent Event [Line Items]          
Shares of common stock issued (in shares)         807,436