Commitments and Contingencies We lease office and warehouse facilities, vehicles and office equipment under operating lease agreements, which include both monthly and longer-term arrangements. Leases with initial terms of one year or more expire at various dates through 2025 and generally provide for extension options. Rent expense under the leasing agreements (exclusive of real estate taxes, insurance and other expenses payable under the leases) amounted to $18,640 , $17,804 and $18,446 in 2016 , 2015 and 2014 , respectively. The minimum rentals for aggregate lease commitments as of December31, 2016 , were as follows: 2017 $ 8,866 2018 5,056 2019 3,334 2020 1,852 2021 948 Thereafter 1,202 Total $ 21,258 Certain operating leases for vehicles contain residual value guarantee provisions, which would become due at the expiration of the operating lease agreement if the fair value of the leased vehicles is less than the guaranteed residual value. The aggregate residual value at lease expiration of those leases is $15,571 , of which we have guaranteed $12,549 . As of December31, 2016 , we have recorded a liability for the estimated end-of-term loss related to this residual value guarantee of $483 for certain vehicles within our fleet. Our fleet also contains vehicles we estimate will settle at a gain. Gains on these vehicles will be recognized at the end of the lease term. On March23, 2016 , we entered into a four year Joint Development Agreement with a partner to develop software. As part of that agreement we have committed to spend $3,000 during the first year of the agreement and $8,000 over the life of the agreement, subject to regular time and materials billing and achievement of contract milestones. In the ordinary course of business, we may become liable with respect to pending and threatened litigation, tax, environmental and other matters. While the ultimate results of current claims, investigations and lawsuits involving us are unknown at this time, we do not expect that these matters will have a material