Earnings Per Share - Antidilutive Securities (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2019 shares	Sep. 30, 2018 shares	Sep. 30, 2019 trading_day
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Series J convertible perpetual preferred stock \| shares	16,306	15,703
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%
Threshold consecutive trading days \| trading_day			40

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 40
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1930-109256

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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