19. Commitments

We have commitments under various operating leases with initial terms greater than one year for machinery and facilities. These leases have terms that will expire on various dates through 2025. 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 our Commercial Agreements with Western.

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, 2014 (in thousands):



2015	$	8,050
2016	6,560
2017	4,360
2018	1,621
2019	577
2020 and thereafter	325
	$	21,493

Total rental expense was $8.8 million, $6.4 million and $6.2 million for the years ended December 31, 2014, 2013 and 2012, respectively. Contingent rentals and subleases were not significant in any year.