Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.8.0.1
Document and Entity Information - USD ($)
$ in Billions
12 Months Ended
Dec. 31, 2017
Feb. 21, 2018
Jun. 30, 2017
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Trading Symbol HASI    
Entity Registrant Name Hannon Armstrong Sustainable Infrastructure Capital, Inc.    
Entity Central Index Key 0001561894    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   53,348,376  
Entity Public Float     $ 1.2