12. 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. Certain of our lease agreements provide for the fair value purchase of the leased asset at the end of the lease. 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.

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, 2013 (in thousands):



2014	$	42
2015	5
2016	5
2017	5
2018	5
2019 and thereafter	37
	$	99

Total rental expense was $0.58 million, $0.06 million and $0.06 million for the years ended December 31, 2013, 2012 and 2011, respectively. Contingent rentals and subleases were not significant in any year.