Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Payment terms for customers, lower range	30 days
Payment term for customers, upper range	180 days
Total	$ 36.8
Revenue, Remaining Performance Obligation, Percentage	80.00%
Unearned revenue and customer deposits	$ 54.1	$ 59.1
Other Current Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Unearned revenue and customer deposits	1.5	1.5
Other Noncurrent Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Contract liabilities, recognized, noncurrent	$ 26.7	$ 27.1
Minimum [Member]
Disaggregation Of Revenue [Line Items]
Customer contract term	1 year
SEA-US contract term	15 years
Indefeasible right of use of contract term	15 years
Maximum [Member]
Disaggregation Of Revenue [Line Items]
Customer contract term	5 years
SEA-US contract term	25 years
Indefeasible right of use of contract term	25 years
Indefeasible Right of Use, Maximum, in Years	30 years