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, 2015 are as follows (in thousands): Years ending December 31: 2016 $ 155,104 2017 134,774 2018 113,440 2019 91,927 2020 75,084 Thereafter 286,127 Future Minimum Lease Payments $ 856,456 Rental expense for operating leases was approximately $168.4 million , $148.5 million and $122.4 million during the years ended December 31, 2015 , 2014 and 2013 , 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, 2015 , our portion of the guaranteed residual value would have totaled approximately $32.9 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.