restricted cash and marketable securities as of december 31 , 2018 , we had $ 108.1 million of restricted cash and marketable securities of which $ 78.6 million supports our insurance programs for workers 2019 compensation , commercial general liability , and commercial auto liability . additionally , we obtain funds through the issuance of tax-exempt bonds for the purpose of financing qualifying expenditures at our landfills , transfer stations , collection and recycling processing centers