XML 15 R44.htm IDEA: XBRL DOCUMENT v3.20.1
Common Stock (Details) - USD ($)
1 Months Ended 3 Months Ended 12 Months Ended
Dec. 30, 2019
Sep. 30, 2018
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Mar. 31, 2019
Dec. 31, 2019
Jul. 31, 2019
Apr. 30, 2019
May 31, 2018
Class of Stock [Line Items]                    
Common Stock, Shares Authorized     90,000,000 90,000,000     90,000,000      
Proceeds From Issuance Of Common Stock     $ 104,615,000     $ 57,845,000        
Preferred stock, par value (in dollars per share)     $ 0.0001 $ 0.0001     $ 0.0001      
Preferred stock, shares authorized     4,000,000 4,000,000     4,000,000      
Common Stock [Member]                    
Class of Stock [Line Items]                    
Stock Issued During Period, Shares, New Issues     1,400,251     874,268        
Common Stock [Member] | Forward Sale Agreement [Member]                    
Class of Stock [Line Items]                    
Common Stock, Shares Authorized   3,500,000             3,162,500  
Stock Issued During Period, Shares, New Issues   3,500,000         3,162,500      
Proceeds From Issuance Of Common Stock $ 195,800,000 $ 186,000,000.0                
At-Market Equity Program [Member]                    
Class of Stock [Line Items]                    
Value Of Equity Instruments To Be Issued                   $ 250,000,000.0
At-Market Equity Program [Member] | Common Stock [Member]                    
Class of Stock [Line Items]                    
Value Of Equity Instruments To Be Issued     $ 0              
At-Market Equity Program Two [Member] | Common Stock [Member]                    
Class of Stock [Line Items]                    
Forward Contract Indexed to Issuer's Equity, Shares       2,003,118            
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value     758,000              
Stock Issued During Period, Shares, New Issues     1,245,118   444,228          
Proceeds From Issuance Of Common Stock         $ 33,000,000.0          
Value Of Equity Instruments To Be Issued               $ 400,000,000.0    
Common stock Average Price         $ 74.30          
At-Market Equity Program Three [Member] | Common Stock [Member]                    
Class of Stock [Line Items]                    
Common Stock, Shares Authorized     3,169,754              
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value     3,014,621              
Stock Issued During Period, Shares, New Issues     155,133              
Value Of Equity Instruments To Be Issued     $ 0              
At-Market Equity Program Four [Member]                    
Class of Stock [Line Items]                    
Value Of Equity Instruments To Be Issued     $ 400,000,000.0              
At-Market Equity Program Four [Member] | Common Stock [Member]                    
Class of Stock [Line Items]                    
Forward Contract Indexed to Issuer's Equity, Shares     204,074              
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value     204,074              
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Cash, at Fair Value     $ 387,300,000              
Stock Issued During Period, Shares, New Issues     0              
Over-Allotment Option [Member] | Common Stock [Member] | Forward Sale Agreement [Member]                    
Class of Stock [Line Items]                    
Common Stock, Shares Authorized                 412,500