CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2020 $ / shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 $ / shares	Dec. 31, 2019 USD ($)
Defined benefit plan, tax | $		$ 0.4		$ (0.1)
Series 1
Dividends on preferred shares of a subsidiary company (in CAD per share)	$ 1.212500		$ 1.212500
Series 2
Dividends on preferred shares of a subsidiary company (in CAD per share)	1.434752		1.392500
Series 3
Dividends on preferred shares of a subsidiary company (in CAD per share)	$ 1.288117		$ 1.459115