Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Reconciliation of Undiscounted Amount to Recorded Balance

The table below summarizes our environmental liability accruals (in millions):

	December 31,
	2017		2016
Discounted environmental liabilities	$	33.7	$	2.2
Undiscounted environmental liabilities	42.4		5.0
Total accrued environmental liabilities	$	76.1	$	7.2

As of December 31, 2017, the estimated future payments of environmental obligations for which discounts have been applied are as follows (in millions):

2018	$	1.9
2019	1.9
2020	1.9
2021	1.9
2022	1.9
Thereafter	37.7
Discounted environmental liabilities, gross	47.2
Less: Discount applied	13.5
Discounted environmental liabilities	$	33.7

Schedule of Future Minimum Rental Payments for Operating Leases

The following is an estimate of our future minimum lease payments for operating leases having remaining noncancelable terms in excess of one year as of December 31, 2017 (in millions):

2018	$	52.8
2019	42.7
2020	35.3
2021	27.4
2022	22.2
Thereafter	102.5
Total future minimum rentals	$	282.9