We record a liability for environmental remediation when such liability becomes probable and the costs or damages can be reasonably estimated. We accrue environmental remediation costs, on an undiscounted basis, associated with identified sites where an assessment has indicated that cleanup costs are probable and can be reasonably estimated, but the timing of such payments is not fixed and determinable. Such accruals are based on currently available information, estimated timing of remedial actions, existing technology, and enacted laws and regulations. Our liability for environmental remediation is included on the Consolidated Balance Sheets in current liabilities within Accrued liabilities and in noncurrent liabilities within Other liabilities see Note 7 – Accrued Liabilities And Other Long term Liabilities.

At December 31, 2018 and 2017, the total environmental remediation liabilities recognized were $33.5 million and $30.8 million, respectively, of which $5.3 million and $5.7 million, respectively, were presented in Accrued liabilities on the Consolidated Balance Sheets. We project estimated payments over approximately 30 years.

We have asset retirement obligations that we are required to perform under law or contract once an asset is permanently taken out of service. Most of these obligations are not expected to be paid until many years in the future and are expected to be funded from general company resources at the time of removal.

At December 31, 2018 and 2017, the total asset retirement obligation liabilities recognized were $19.1 million and $18.2 million, respectively, and were included in noncurrent liabilities within Other liabilities see Note 7 – Accrued Liabilities And Other Long term Liabilities.

We lease various plant equipment, office furniture and equipment, motor vehicles, office and warehouse space, and landfills under operating lease agreements. Our leases have varying terms. The leasesmay contain renewal or purchase options, escalation clauses, restrictions, penalties or other obligations that we consider in determining minimum lease payments.

During the years ended December 31, 2018, 2017, and 2016, rent expense, including lease related costs, month-to-month rentals and leases with an initial lease term of less than one year, was $192.1 million, $186.2 million, and $181.6 million, respectively, of which $178.7 million, $173.7 million, and $169.8 million, respectively, was included within COR with the remainder included in SG&A on the Consolidated Statements of (Loss) Income.

Minimum future rental payments under non-cancelable operating leases that have initial or remaining terms in excess of one year as of December 31, 2018 (including leases with an inception date but not yet commenced) for each of the next five years and in the aggregate are as follows:

In millions
2019	$	107.0
2020		88.7
2021		72.7
2022		54.8
2023		40.0
Thereafter		128.7
	$	491.9

The Company has entered into non-cancelable arrangements with third-parties, primarily related to information technology products and services. As of December 31, 2018, future payments under these contractual obligations, which are not recognized on the Consolidated Balance Sheets, were as follows:

In millions
2019	$	21.3
2020		20.5
2021		5.1
2022		-
2023		-
Thereafter		-
	$	46.9

As of December 31, 2018 and 2017, we had $63.1 million and $130.8 million, respectively, of stand-by letters of credit outstanding against our senior credit facility (see Note 8 – Debt). At December 31, 2018 we also had a further $52.2 million of stand-by letters of credit outstanding against another facility which was entered into during 2018. In addition, at December 31, 2018 and 2017 we had, $63.7 million and $19.0 million, respectively, of surety bonds, and $19.5 million and $15.7 million, respectively, of bank guarantees. The bank guarantees are issued mostly by our international subsidiaries for various purposes, including leases, seller notes, contracts and permits. The surety bonds are used for performance and financial guarantees. Neither the bank guarantees nor the surety bonds affect our ability to use our various lines of credit.