Revenue from Contracts with Customers (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) item segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Revenue from Contracts with Customers [Abstract]
Number of geographic segments | segment	2
Number of revenue streams | item	3
Receivables from contracts with customers	$ 266,500,000		$ 147,600,000
Impairment losses on receivables or contract assets	0	$ 0
Revenue, remaining performance obligation	$ 0