Capital and Accumulated Other Comprehensive Income (Loss) - Redeemable Preferred Units (Details) - USD ($) $ / shares in Units, $ in Thousands								12 Months Ended
	Oct. 10, 2019	Mar. 13, 2019	Sep. 14, 2017	Sep. 07, 2017	Aug. 07, 2017	Aug. 24, 2015	Apr. 09, 2013	Dec. 31, 2020	Dec. 31, 2019	Oct. 15, 2020	Sep. 08, 2020	Apr. 01, 2019
Preferred Units [Line Items]
Liquidation preference								$ 956,250	$ 1,456,250
Balance (in thousands, net of issuance costs) as of December 31,								$ 950,940	$ 1,434,420
Preferred stock, liquidation preference per share/unit (in dollars per unit)								$ 25.00	$ 25.00
Preferred Stock, Redemption Price Per Share								$ 25.00
Series C Preferred Units
Preferred Units [Line Items]
Liquidation preference								$ 201,250
Preferred stock dividend per share amount (in dollars per share)			$ 1.65625
Balance (in thousands, net of issuance costs) as of December 31,								219,250	$ 219,250
Dividend rate percentage			6.625%
Series G Preferred Units
Preferred Units [Line Items]
Preferred stock dividend per share amount (in dollars per share)							$ 1.46875
Balance (in thousands, net of issuance costs) as of December 31,									241,468
Preferred stock, liquidation preference per share/unit (in dollars per unit)										$ 25.00
Dividend rate percentage							5.875%
Preferred Stock, Redemption Price Per Share										$ 25.057118
Potentially dilutive Series H Cumulative Redeemable Preferred Units
Preferred Units [Line Items]
Preferred stock, liquidation preference per share/unit (in dollars per unit)												$ 25.00
Preferred Stock, Redemption Price Per Share												$ 25.00
Series I Preferred Units
Preferred Units [Line Items]
Preferred stock dividend per share amount (in dollars per share)						$ 1.58750
Balance (in thousands, net of issuance costs) as of December 31,									242,012
Preferred stock, liquidation preference per share/unit (in dollars per unit)											$ 25.00
Dividend rate percentage					6.35%
Preferred Stock, Redemption Price Per Share											$ 25.29545
Series J Preferred Units
Preferred Units [Line Items]
Liquidation preference								200,000
Preferred stock dividend per share amount (in dollars per share)					$ 1.31250
Balance (in thousands, net of issuance costs) as of December 31,								193,540	193,540
Dividend rate percentage				5.25%
Series K Preferred Units
Preferred Units [Line Items]
Liquidation preference								210,000
Preferred stock dividend per share amount (in dollars per share)		$ 1.46250
Balance (in thousands, net of issuance costs) as of December 31,								203,264	203,264
Dividend rate percentage		5.85%
Series L Preferred Units
Preferred Units [Line Items]
Liquidation preference								345,000
Preferred stock dividend per share amount (in dollars per share)	$ 1.30000
Balance (in thousands, net of issuance costs) as of December 31,								$ 334,886	$ 334,886
Dividend rate percentage	5.20%