Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Schedule Of Capital Stock

Changes to the number of shares of capital stock issued were as follows:

	Common stock issued		Exchangeable shares issued
	Class A	Class B	Class A		Class B
	(Share amounts in millions)
Balance as of December 31, 2016	2.6	203.7	2.9		15.2
Shares issued under equity compensation plans	—	0.5	—		—
Shares exchanged for common stock	—	0.5	—		(0.5	)
Balance as of December 31, 2017	2.6	204.7	2.9		14.7
Shares issued under equity compensation plans	—	0.7	—		—
Shares exchanged for Class B exchangeable shares	—	—	(0.1	)	0.1
Balance as of December 31, 2018	2.6	205.4	2.8		14.8
Shares issued under equity compensation plans	—	0.2	—		—
Shares exchanged for common stock	—	0.1	—		(0.1	)
Shares exchanged for Class B exchangeable shares	—	—	(0.1	)	0.1
Balance as of December 31, 2019	2.6	205.7	2.7		14.8