Related Party Transactions and Arrangements - Investments in SMTA (Details) - USD ($)
3 Months Ended 6 Months Ended
May 31, 2018
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Related Party Transaction [Line Items]            
Preferred stock, shares issued   6,900,000   6,900,000   6,900,000
Dividend rate       6.00%    
Preferred stock, liquidation preference (in USD per share)   $ 25.00   $ 25.00    
Preferred dividend income from SMTA   $ 3,750,000 $ 1,250,000 $ 7,500,000 $ 1,250,000  
Preferred equity investment in SMTA   150,000,000   150,000,000   $ 150,000,000
Affiliated Entity            
Related Party Transaction [Line Items]            
Preferred dividend income from SMTA   3,800,000   7,500,000    
Dividends receivable   $ 3,800,000   $ 3,800,000   $ 3,800,000
Spirit MTA REIT | Affiliated Entity            
Related Party Transaction [Line Items]            
Preferred stock, shares issued 6,000,000.0          
Aggregate liquidation preference amount $ 150,000,000.0          
Dividend rate 10.00%          
Preferred stock, liquidation preference (in USD per share) $ 25.00          
Liquidation value on a quarterly basis (in USD per share) 0.625          
Liquidation value on an annual basis (in USD per share) $ 2.50