Fair Value Measurements and Derivative Instruments (Narrative) (Details) - USD ($)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 01, 2017
Fair Value Measurements And Derivative Instruments [Line Items]
Fair value, assets, transfers Level 1 to Level 2	$ 0	$ 0
Fair value, assets, transfers Level 2 to Level 1	0	0
Fair value, liabilities, transfers Level 1 to Level 2	0	0
Fair value, liabilities, transfers Level 2 to Level 3	0	0
Fair value, assets and liabilities, transfers into/(out of) Level 3	0	0
Interest Rate Derivatives [Member]
Fair Value Measurements And Derivative Instruments [Line Items]
Net gain (loss) on interest rate instruments	$ (189,000)	$ 427,000
Redemption Rights [Member] \| Series E Preferred Stock [Member]
Fair Value Measurements And Derivative Instruments [Line Items]
Number of shares called by redemption			490,250

Fair Value Measurements And Derivative Instruments [Line Items]

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

+ References

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- Definition

Amount of gain (loss) included in earnings for the period from the increase (decrease) in fair value of interest rate derivatives not designated as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
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