Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Earnings Per Share (Anti-dilutive Shares) (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2018 trading_day shares	Mar. 31, 2017 shares	Oct. 31, 2017	Oct. 20, 2017	Sep. 30, 2017
Series J convertible perpetual preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares (in shares)	0	15,635
Joint venture shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares (in shares)	0	298
3.125% senior convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stated interest rates (as a percent)	3.125%		3.125%	3.125%	3.125%
Threshold consecutive trading days \| trading_day	40