Commitments and Contingencies - Narrative (Details)
$ in Millions
3 Months Ended
Nov. 25, 2015
USD ($)
Mar. 31, 2017
USD ($)
Property
tenant
claim
location
Apr. 01, 2016
USD ($)
Sep. 08, 2015
Property
Loss Contingencies [Line Items]        
Number of locations sold | Property   6    
Proceeds from sale of locations | $   $ 56.6    
Number of leases sold which were previously rejected | location   4    
Number of locations owned with in-place leases | location   11    
Number of vacant properties | location   3    
Outstanding claims | claim   0    
Total commitments | $   $ 59.0    
Total commitments relating to future acquisitions | $   4.7    
Funded commitments | $   58.1    
Contingently liable amount of debt owed by tenant | $   $ 5.7    
Number of tenants indemnified by | tenant   1    
Haggen Operations Holdings, LLC        
Loss Contingencies [Line Items]        
Number of leased properties | Property       20
Albertons, LLC        
Loss Contingencies [Line Items]        
Amount of bankruptcy claims for rent reduction settled | $     $ 3.0  
Haggen Operations Holdings, LLC        
Loss Contingencies [Line Items]        
Amount of bankruptcy claims settled | $     $ 3.4  
Locations returned upon settlement | location   7    
Number of lease location affirmed under bankruptcy | location   13    
Haggen Operations Holdings, LLC | Albertson's LLC        
Loss Contingencies [Line Items]        
Number of lease location affirmed under bankruptcy | location   5    
Haggen Operations Holdings, LLC | Smart and Final LLC        
Loss Contingencies [Line Items]        
Number of lease location affirmed under bankruptcy | location   5    
Haggen Operations Holdings, LLC | Gleason's Markets        
Loss Contingencies [Line Items]        
Number of lease location affirmed under bankruptcy | location   2    
Haggen Operations Holdings, LLC | Safeway        
Loss Contingencies [Line Items]        
Number of lease location affirmed under bankruptcy | location   1    
Haggen Operations Holdings, LLC Bankruptcy Claim        
Loss Contingencies [Line Items]        
Stipulated claims collected | $   $ 5.5    
Spirit Realty, Inc. | Haggen Operations Holdings, LLC        
Loss Contingencies [Line Items]        
Initial litigation settlement | $ $ 21.0