Planned spin-off transaction (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Spin-off [Abstract]
Separation costs	$ 9.4	$ 0.0	$ 9.4	$ 0.0