Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

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- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12A
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL108322424-203045

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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.

+ References

No definition available.

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Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
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Revenue Recognition (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
Revenue Recognition (Narrative) (Details) - USD ($)	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue recognized	$ 8,037,000	$ 5,428,000	$ 11,522,000	$ 7,252,000
Revenue recognized from performance obligations satisfied in prior periods			$ 0
Individual Counterparty [Member]
Disaggregation of Revenue [Line Items]
Duration of contract with customer (less than)	1 year		1 year
Residential Real Estate [Member] \| Individual Counterparty [Member]
Disaggregation of Revenue [Line Items]
Revenue recognized	$ 7,180,000	$ 5,423,000	$ 9,840,000	$ 7,016,000