Reinsurance retention

  
In 2021, 2020 and 2019, the reserve for loss and loss expense in the consolidated balance sheets also included $76 million, $69 million and $59 million, respectively, for certain life and health loss and loss expense reserves. Additional disclosures for reserves related to these health claims are not material and therefore not provided.  
During 2021, we experienced $428 million of favorable development on prior accident years including $353 million of favorable development in commercial lines, $50 million of favorable development in personal lines and $7 million of unfavorable development in excess and surplus lines. Within commercial lines, we recognized favorable development of $120 million for the commercial casualty line, $97 million for the commercial property line,$66 million for the workers' compensation line and $43 million for the commercial auto line due to reduced uncertainty of prior accident year loss and loss expense for these lines. Within personal lines, we recognized favorable reserve development of $31 million in personal auto and $14 million for the homeowner line of business.   
During 2020, we experienced $131 million of favorable development on prior accident years including $95 million of favorable development in commercial lines, $18 million of favorable development in personal lines and $7 million of unfavorable development in excess and surplus lines. Within commercial lines, we recognized favorable development of $54 million for the commercial casualty line, $39 million for the workers' compensation line and $16 million for the commercial property line due to reduced uncertainty of prior accident year loss and loss expense for these lines. This was partially offset by unfavorable development of $17 million for the commercial auto line. Within personal lines, we recognized favorable reserve development of $15 million in personal auto and $5 million for the homeowner line of business.   
During 2019, we experienced $248 million of favorable development on prior accident years including $192 million of favorable development in commercial lines, $27 million of favorable development in personal lines and$11 million of favorable development in excess and surplus lines. Within commercial lines, we recognized favorable development $78 million for the commercial casualty line, $77 million for the workers' compensation line, $25 million for the commercial property line and $6 million for the commercial auto line due to reduced uncertainty of prior accident year loss and loss expense for these lines. Within personal lines, we recognized favorable reserve development of $26 million in personal auto. We recognized unfavorable reserve development of $11 million for the homeowner line of business due primarily to higher-than-anticipated loss development on known claims.  
Included in our lines of business are asbestos and environmental claims. We carried $88 million and $85 million of net loss and loss expense reserves for asbestos and environmental claims at December 31, 2021 and 2020, respectively. The asbestos and environmental claims amounts for each respective year constituted less than 2.0% of total net loss and loss expense reserves at these year-end dates. We believe our exposure to asbestos and environmental claims is limited, largely because our reinsurance retention was $500,000 or below prior to 1987. We also were predominantly a personal lines company in the 1960s and 1970s. During the 1980s and early 1990s, commercial lines grew as a percentage of our overall business and our exposure to asbestos and environmental claims grew accordingly. Over that period, we included an asbestos and environmental exclusion in almost all policies or endorsed the exclusion to the policies. We have no exposure to asbestos and environmental claims related to our acquisition of Cincinnati Global. We continue to monitor our claims for evidence of material exposure to other mass tort classes but have found no such credible evidence to date.  
Cincinnati Financial Corporation - 2021 10-K - Page 142
