Shareholders' Equity / Partners' Capital - Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Mar. 31, 2018
Class A common shares/units
Class of Stock [Line Items]
Repurchase of class A common stock, authorized amount			$ 300,000,000.0
Weighted-average price of shares (in dollars per share)	$ 19.36
Total cost of class A common shares	$ 34,900,000
Remaining repurchase authorization amount		$ 265,100,000
Class A common shares/units | Common Stock
Class of Stock [Line Items]
Repurchases and retire of class A common shares (in shares)	1.8
Preferred shares
Class of Stock [Line Items]
Repurchase of class A common stock, authorized amount		$ 250,000,000.0	$ 250,000,000.0