Income Taxes - Components of Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating losses	$ 150.1	$ 112.7
Interest carryforward	88.4	69.3
Capital loss carryforward	53.6	66.6
Tax credits	28.8	33.8
Employee benefits	21.3	22.2
Research and development costs	21.2	18.4
Unrealized foreign exchange	0.0	9.9
Accrued liabilities	6.7	5.3
Other	21.7	19.8
Total deferred tax assets	391.8	358.0
Valuation allowances	(199.1)	(219.6)
Total gross deferred tax assets	192.7	138.4
Deferred tax liabilities:
Intangible assets	179.6	198.0
Property, plant and equipment	21.5	17.9
Undistributed foreign earnings	18.3	9.9
Goodwill	9.0	6.3
Total gross deferred tax liabilities	228.4	232.1
Net deferred tax liability	$ 35.7	$ 93.7