CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Class A Common Stock
Increase (Decrease) in Stockholders' Equity
Treasury stock repurchases (in shares)	0	2,279,373	0	3,892,405
Common Stock
Increase (Decrease) in Stockholders' Equity
Dividends declared per share of common stock (dollars per share)	$ 0.01	$ 0.10	$ 0.12	$ 0.30
Dividends declared and paid per share of common stock (dollars per share)	$ 0.01	$ 0.10	$ 0.12	$ 0.29
Common Stock | Class A Common Stock
Increase (Decrease) in Stockholders' Equity
Grant of exchangeability, redemption and issuance of limited partnership interests and issuance of common stock (in shares)	818,689	588,972	2,364,664	1,965,195
Treasury stock repurchases (in shares)		2,279,373		3,892,405