Distributions Paid and Payable - Common Stock (Details) - Common stock - $ / shares	1 Months Ended	3 Months Ended
Mar. 31, 2018	Feb. 28, 2018	Jan. 31, 2018	Mar. 31, 2017	Feb. 28, 2017	Jan. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Distributions Paid and Payable
Total common stock dividends paid per share (in dollars per share)	$ 0.2190	$ 0.2190	$ 0.2125	$ 0.2105	$ 0.2105	$ 0.2025	$ 0.6505	$ 0.6235
Monthly distributions payable (in dollars per share)	$ 0.2195						$ 0.2195

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

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

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