Related Parties (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	$ 1.4	$ 1.7	$ 2.9	$ 3.3