business subsequent to the acquisition . the liabilities for these payments are classified as level 3 liabilities because the related fair value measurement , which is determined using an income approach , includes significant inputs not observable in the market . financial assets and liabilities not measured at fair value our debt is reflected on the consolidated balance sheets at cost . based on market conditions as of december 31 , 2018 and 2017 , the fair value of our credit agreement borrowings reasonably approximated the carrying values of $ 1.7 billion and $ 2.0 billion , respectively . in addition , based on market conditions , the fair values of the outstanding borrowings under the receivables facility reasonably approximated the carrying values of $ 110 million and $ 100 million at december 31 , 2018 and december 31 , 2017 , respectively . as of december 31 , 2018 and december 31 , 2017 , the fair values of the u.s . notes ( 2023 ) were approximately $ 574 million and $ 615 million , respectively , compared to a carrying value of $ 600 million at each date . as of december 31 , 2018 and december 31 , 2017 , the fair values of the euro notes ( 2024 ) were approximately $ 586 million and $ 658 million compared to carrying values of $ 573 million and $ 600 million , respectively . as of december 31 , 2018 , the fair value of the euro notes ( 2026/28 ) approximated the carrying value of $ 1.1 billion . the fair value measurements of the borrowings under our credit agreement and receivables facility are classified as level 2 within the fair value hierarchy since they are determined based upon significant inputs observable in the market , including interest rates on recent financing transactions with similar terms and maturities . we estimated the fair value by calculating the upfront cash payment a market participant would require at december 31 , 2018 to assume these obligations . the fair value of our u.s . notes ( 2023 ) is classified as level 1 within the fair value hierarchy since it is determined based upon observable market inputs including quoted market prices in an active market . the fair values of our euro notes ( 2024 ) and euro notes ( 2026/28 ) are determined based upon observable market inputs including quoted market prices in markets that are not active , and therefore are classified as level 2 within the fair value hierarchy . note 13 . commitments and contingencies operating leases we are obligated under noncancelable operating leases for corporate office space , warehouse and distribution facilities , trucks and certain equipment . the future minimum lease commitments under these leases at december 31 , 2018 are as follows ( in thousands ) : years ending december 31: .
at december 31 , 2018 what was the percent of the total future minimum lease commitments under the leases that was due in 2020
rental expense for operating leases was approximately $ 300 million , $ 247 million , and $ 212 million during the years ended december 31 , 2018 , 2017 and 2016 , respectively . we guarantee the residual values of the majority of our truck and equipment operating leases . the residual values decline over the lease terms to a defined percentage of original cost . in the event the lessor does not realize the residual value when a piece of equipment is sold , we would be responsible for a portion of the shortfall . similarly , if the lessor realizes more than the residual value when a piece of equipment is sold , we would be paid the amount realized over the residual value . had we terminated all of our operating leases subject to these guarantees at december 31 , 2018 , our portion of the guaranteed residual value would have totaled approximately $ 76 million . we have not recorded a liability for the guaranteed residual value of equipment under operating leases as the recovery on disposition of the equipment under the leases is expected to approximate the guaranteed residual value . litigation and related contingencies we have certain contingencies resulting from litigation , claims and other commitments and are subject to a variety of environmental and pollution control laws and regulations incident to the ordinary course of business . we currently expect that the resolution of such contingencies will not materially affect our financial position , results of operations or cash flows. .