Related Parties (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transactions [Abstract]
Net accounts receivable, related parties	$ 0.6		$ 0.6		$ 0.5
Accounts payable and accrued expenses, related parties	0.3		0.3		$ 0.7
Joint venture fee income	$ 1.9	$ 1.3	$ 4.8	$ 4.6