Income Taxes - Distributions (Details) - $ / shares					1 Months Ended	12 Months Ended
	Dec. 15, 2021	Dec. 15, 2020	Dec. 16, 2019	Dec. 14, 2018	Dec. 14, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0.5609
Ordinary non-qualified income, percent						0.00%	0.00%	30.03%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0.0069
Qualified dividend, percent						0.00%	0.00%	0.37%
Capital gain (in usd per share)						$ 0.0128	$ 0.0100	$ 1.3000
Capital gain, percent						32.00%	33.33%	69.60%
Return of capital (in usd per share)						$ 0.0272	$ 0.0200	$ 0
Return of capital, percent						68.00%	66.67%	0.00%
Total (in usd per share)						$ 0.0400	$ 0.0300	$ 1.8678
Total, percent						100.00%	100.00%	100.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)	$ 0.0100	$ 0.0100			$ 0.3478
Distributions declared, treated as distributions for taxes in prior year (in usd per share)			$ 0.3800
Series C Cumulative Redeemable Preferred Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0.6100
Ordinary non-qualified income, percent						0.00%	0.00%	30.03%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0.0075
Qualified dividend, percent						0.00%	0.00%	0.37%
Capital gain (in usd per share)						$ 0.1725	$ 0.4063	$ 1.4138
Capital gain, percent						12.45%	33.34%	69.60%
Return of capital (in usd per share)						$ 1.2133	$ 0.8125	$ 0
Return of capital, percent						87.55%	66.66%	0.00%
Total (in usd per share)						$ 1.3858	$ 1.2188	$ 2.0313
Total, percent						100.00%	100.00%	100.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)				$ 0.4063
Series D Cumulative Redeemable Preferred Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0.5982
Ordinary non-qualified income, percent						0.00%	0.00%	30.03%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0.0074
Qualified dividend, percent						0.00%	0.00%	0.37%
Capital gain (in usd per share)						$ 0.1692	$ 0.3984	$ 1.3866
Capital gain, percent						12.49%	33.33%	69.60%
Return of capital (in usd per share)						$ 1.1855	$ 0.7969	$ 0
Return of capital, percent						87.51%	66.67%	0.00%
Total (in usd per share)						$ 1.3547	$ 1.1953	$ 1.9922
Total, percent						100.00%	100.00%	100.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)				0.3984
Series E Cumulative Redeemable Preferred Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0.5982
Ordinary non-qualified income, percent						0.00%	0.00%	30.03%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0.0074
Qualified dividend, percent						0.00%	0.00%	0.37%
Capital gain (in usd per share)						$ 0.5118	$ 0.3984	$ 1.3866
Capital gain, percent						32.11%	33.33%	69.60%
Return of capital (in usd per share)						$ 1.0819	$ 0.7969	$ 0
Return of capital, percent						67.89%	66.67%	0.00%
Total (in usd per share)						$ 1.5937	$ 1.1953	$ 1.9922
Total, percent						100.00%	100.00%	100.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)	0.3984			0.3984
Series F Cumulative Redeemable Preferred Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0.5912
Ordinary non-qualified income, percent						0.00%	0.00%	30.03%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0.0073
Qualified dividend, percent						0.00%	0.00%	0.37%
Capital gain (in usd per share)						$ 0.5058	$ 0.3938	$ 1.3703
Capital gain, percent						32.11%	33.34%	69.60%
Return of capital (in usd per share)						$ 1.0692	$ 0.7875	$ 0
Return of capital, percent						67.89%	66.66%	0.00%
Total (in usd per share)						$ 1.5750	$ 1.1813	$ 1.9688
Total, percent						100.00%	100.00%	100.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)	0.3938			$ 0.3938
Series G Cumulative Redeemable Preferred Shares
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0
Ordinary non-qualified income, percent						0.00%	0.00%	0.00%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0
Qualified dividend, percent						0.00%	0.00%	0.00%
Capital gain (in usd per share)						$ 0.5787	$ 0	$ 0
Capital gain, percent						86.00%	0.00%	0.00%
Return of capital (in usd per share)						$ 0.0942	$ 0	$ 0
Return of capital, percent						14.00%	0.00%	0.00%
Total (in usd per share)						$ 0.6729	$ 0	$ 0
Total, percent						100.00%	0.00%	0.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)	0.3984
Series H Cumulative Redeemable Preferred Stock
Real Estate Investment Trust Distributions [Line Items]
Ordinary non-qualified income (in usd per share)						$ 0	$ 0	$ 0
Ordinary non-qualified income, percent						0.00%	0.00%	0.00%
Qualified dividend (in usd per share)						$ 0	$ 0	$ 0
Qualified dividend, percent						0.00%	0.00%	0.00%
Capital gain (in usd per share)						$ 0.2655	$ 0	$ 0
Capital gain, percent						86.01%	0.00%	0.00%
Return of capital (in usd per share)						$ 0.0432	$ 0	$ 0
Return of capital, percent						13.99%	0.00%	0.00%
Total (in usd per share)						$ 0.3087	$ 0	$ 0
Total, percent						100.00%	0.00%	0.00%
Distributions declared, treated as distributions for taxes in next year (in usd per share)	$ 0.3563