CONDENSED CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000.0	25,000,000.0
Preferred stock, shares issued (in shares)	0	0
Treasury stock, shares (in shares)	9,500,000	9,500,000
Common Class A
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000.0	500,000,000.0
Common stock, shares issued (in shares)	2,600,000	2,600,000
Common stock, shares outstanding (in shares)	2,600,000	2,600,000
Common Class B
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000.0	500,000,000.0
Common stock, shares issued (in shares)	209,800,000	205,700,000
Common stock, shares outstanding (in shares)	209,800,000	205,700,000
Exchangeable Class A
Exchangeable shares, no par value (in dollars per share)	$ 0	$ 0
Exchangeable shares, issued (in shares)	2,700,000	2,700,000
Exchangeable shares, outstanding (in shares)	2,700,000	2,700,000
Exchangeable Class B
Exchangeable shares, no par value (in dollars per share)	$ 0	$ 0
Exchangeable shares, issued (in shares)	11,100,000	14,800,000
Exchangeable shares, outstanding (in shares)	11,100,000	14,800,000