Earnings per share - Antidilutive (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Class A Partnership units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive shares excluded from the computation of diluted net earning per share (in shares)	6,440	6,671	6,453	6,671
Class O units, TSR Units, FFO Units and options to purchase common stock on an "as if" converted basis
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive shares excluded from the computation of diluted net earning per share (in shares)	1,434	1,131	1,372	1,066
Series B Convertible preferred stock on an "as if" converted basis
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive shares excluded from the computation of diluted net earning per share (in shares)	6,787	6,756	6,783	6,753