As of December 31, 2018, we had commitments of approximately $45.0 million for the purchase of property, plant and equipment related to incomplete projects. We also have contractual commitments of approximately $52.5 million for outsourced services, including technology, professional, maintenance and other services. We have a variety of contracts with suppliers for the purchase of paper, ink and other commodities for delivery in future years at prevailing market prices.

Year Ended December 31	Amount
2019	$	77.8
2020		56.9
2021		41.3
2022		27.7
2023		21.4
2024 and thereafter		33.4
	$	258.5

We have operating lease commitments, including those for vacated facilities, totaling $258.5 million extending through various periods to 2028. Future rental commitments for leases have not been reduced by minimum non-cancelable sublease rentals aggregating approximately $7.6 million. We remain secondarily liable under these leases in the event that the sub-lessee defaults under the sublease terms. We do not believe that material payments will be required as a result of the secondary liability provisions of the primary lease agreements.

Rent expense for facilities in use and equipment was $110.0 million, $118.3 million and $117.6 million for the years ended December 31, 2018, 2017 and 2016, respectively. Rent expense for vacated facilities was recognized as net restructuring, impairment and other charges. See Note 5, Restructuring, Impairment and Other Charges, for further discussion.

We are subject to laws and regulations relating to the protection of the environment. We provide for expenses associated with environmental remediation obligations when such amounts are probable and can be reasonably estimated. Such accruals are adjusted as new information develops or circumstances change and are generally not discounted. We have been designated as a potentially responsible party or have received claims in two active federal and state Superfund and other multiparty remediation sites. In addition to these sites, we may also have the obligation to remediate six other previously and currently owned facilities. At the Superfund sites, the Comprehensive Environmental Response, Compensation and Liability Act provides that our liability could be joint and several, meaning that we could be required to pay an amount in excess of our proportionate share of the remediation costs.

Our understanding of the financial strength of other potentially responsible parties at the multiparty sites and of other liable parties at the previously owned facilities has been considered, where appropriate, in the determination of our estimated liability. We believe that our recorded reserves, recorded in Accrued liabilities and other and Other noncurrent liabilities, are adequate to cover our share of the potential costs of remediation at each of the multiparty sites and the previously and currently owned facilities. It is not possible to quantify with certainty the potential impact of actions regarding environmental matters, particularly remediation and other compliance efforts that we may undertake in the future. However, in our opinion, compliance with the present environmental protection laws, before taking into account estimated recoveries from third parties, will not have a material effect on our consolidated results of operations, financial position or cash flows.

From time to time, our clients and others file voluntary petitions for reorganization under United States bankruptcy laws. In such cases, certain pre-petition payments received by us from these parties could be considered preference items and subject to return. In addition, we may be party to certain litigation arising in the ordinary course of business. We believe that the final resolution of these preference items and litigation will not have a material effect on our consolidated results of operations, financial position or cash flows.