Supplemental Balance Sheet Information - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) purchaser	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Supplemental Balance Sheet Disclosures [Line Items]
Reserves and allowances	$ 0.4		$ 0.4
Accounts receivable sold		$ 1.2
Proceeds from sale of accounts receivable		$ 1.1
Repurchase of accounts receivable, term		5 months
Interest per month on receivables sold		2.00%
Income taxes receivable	2.2
Other Noncurrent Assets
Supplemental Balance Sheet Disclosures [Line Items]
Income taxes receivable	2.2
Equity securities	4.0
Other Current Liabilities
Supplemental Balance Sheet Disclosures [Line Items]
Deferred revenue	7.4		7.2
Levy accruals	5.8		5.6
Accrued payroll	1.5		1.5
Other Liabilities
Supplemental Balance Sheet Disclosures [Line Items]
Pension liabilities	$ 24.4		$ 24.4
Obligation to Repurchase Receivables Sold | Threatened Litigation
Supplemental Balance Sheet Disclosures [Line Items]
Number of accounts receivable purchasers with outstanding demands | purchaser	2
Loss contingency, damages sought	$ 0.5