Shareholders' Equity/Partners' Capital - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Jan. 11, 2018	Jan. 04, 2018	Jun. 30, 2018
Class of Stock [Line Items]
Preferred unit issuance costs			$ 14,486
Series G & I Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price per share	$ 25.00	$ 25.00
Preferred stock, redemption amount			470,000
Preferred unit issuance costs			$ 14,486
Redeemable Preferred Stock | Series G Preferred Stock
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage	6.625%	6.625%
Redeemable Preferred Stock | Series I Preferred Stock
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage	6.625%	6.625%