XML 77 R66.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value Disclosures - Additional Information (Detail) - USD ($) | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Impairment charges | $ 558,000 | $ 0
Washington D.C. [Member] |  |
Fair Value, Option, Quantitative Disclosures [Line Items] |  |
Impairment charges | $ 558,000 | $ 0

X
- Definition 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. + Details
Name: | us-gaap_FairValueOptionQuantitativeDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The charge against earnings in the period to reduce the carrying amount of real property to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
Name: | us-gaap_ImpairmentOfRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementGeographicalAxis=stpr_DC
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |