19. Commitments

We have commitments under various operating leases with initial terms greater than one year for property, machinery and facilities. These leases have terms that will expire on various dates through 2026. We expect that in the normal course of business, these leases will be renewed or replaced by other leases. Rent expense for operating leases that provide for periodic rent escalations or rent holidays over the term of the lease is recognized on a straight-line basis. We also have commitments to purchase minimum volumes of refined product from Western under commercial agreements that we have entered into with Western. See Note 21, Related Party Transactions, for further discussion of these agreements.

The following table presents our annual minimum rental payments under non-cancelable operating leases that have lease terms of one year or more as of December 31, 2016 (in thousands):



2017	$	7,289
2018	4,568
2019	2,376
2020	702
2021	349
2022 and thereafter	369
	$	15,653

Total rental expense was $9.2 million, $9.2 million and $8.8 million for the years ended December 31, 2016, 2015 and 2014, respectively. Contingent rentals and subleases were not significant in any year.