Income taxes (Tables)

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

	Three Months Ended September 30,					Nine Months Ended September 30,
	2017			2016		2017			2016
Continuing operations
Provision for income taxes (in millions)	$	16.4		19.5		$	48.1		43.4
Effective tax rate	43.7		%	43.0	%	39.0		%	60.1	%