Income Taxes - Net Operating Losses and Income Tax Concessions (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income taxes
Net operating losses		$ 375.9	$ 275.3
Deffered tax asset		40.1	33.7
Net operating loss carryforward, Total		40.1	33.7
Valuation allowance		32.5	24.3
Valuation allowance, deferred tax asset for NOLs		27.1
Period applicable for additional special income tax concession	5 years
Decrease in foreign income tax		$ 4.3	$ 0.0	$ 1.3
Basic earnings per common share (in dollars per share)		$ 0.07	$ 0	$ 0.02
Diluted earnings per common share (in dollars per share)		$ 0.06	$ 0	$ 0.02
2020-2039
Income taxes
Net operating Loss carryforward, US		$ 11.2
Net operating Loss carryforward, Foreign		3.1
Indefinite
Income taxes
Net operating Loss carryforward, US		2.5
Net operating Loss carryforward, Foreign		$ 23.3