Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of Remaining Performance Obligation

The Company expects to recognize the remaining performance obligations as revenue in future periods as follows:

(millions) (unaudited)	Remaining Performance Obligations
2019	$	43.1
2020	36.1
2021	24.0
2022	10.5
2023	7.2
2024 and thereafter	6.0
Total	$	126.9

Schedule of Contract with Customer, Asset and Liability

The following table provides information about accounts receivable, contract assets and contract liabilities with customers and clients as of March 31, 2019 (unaudited) and December 31, 2018:

(millions)	March 31, 2019			December 31, 2018
Accounts receivable	$	145.9		$	139.3
Contract asset	$	10.3		$	11.4
Contract liability	$	(14.3	)	$	(19.1	)

The following table provides information about changes to contract asset balances for the three-month periods ended March 31, 2019 and 2018:

	Three Months Ended
(millions) (unaudited)	March 31, 2019			March 31, 2018
Balance, beginning of period	$	11.4		$	12.2
Additional contract assets	32.9			35.2
Reclassification to accounts receivable	(34.0		)	(35.4		)
Balance, end of period	$	10.3		$	12.0

The following table provides information about changes to contract liability balances for the three-month periods ended March 31, 2019 and 2018:

	Three Months Ended
(millions) (unaudited)	March 31, 2019			March 31, 2018
Balance, beginning of period	$	19.1		$	20.5
Additional contract liabilities	40.7			44.0
Recognition of revenue from contract liabilities	(45.5		)	(48.2		)
Balance, end of period	$	14.3		$	16.3

Schedule of Amortization Expense Related to Cost of Contracts

The table below shows amortization expense related to cost of contracts for the three-month periods ended March 31, 2019 and 2018. Amortization expense of cost of contracts related to service concession arrangements within the scope of Topic 853 is recorded as a reduction of revenue and was not significant for the three ended March 31, 2019 and 2018, respectively.

	Three Months Ended
(millions) (unaudited)	March 31, 2019		March 31, 2018
Amortization expense related to cost of contract included in depreciation and amortization	$	0.5	$	0.8