Shareholders' Equity / Partners' Capital - Share Repurchase (Details) - USD ($) $ / shares in Units, shares in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2019	Feb. 28, 2018
Class A common shares/units
Class of Stock [Line Items]
Repurchase of shares, authorized amount			$ 300,000,000.0
Average price per share of Class A common shares (in dollars per share)	$ 19.36
Stock repurchased and retired during period	$ 34,900,000
Remaining repurchase authorization		$ 265,100,000
Class A common shares/units | Common Stock
Class of Stock [Line Items]
Repurchases of Class A common shares (in shares)	1.8
Preferred Shares/Units
Class of Stock [Line Items]
Repurchase of shares, authorized amount		$ 250,000,000.0	$ 250,000,000.0