XML 114 R91.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Future Minimum Rents Narrative (Details) - tenants | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Future Minimum Rent [Line Items] |  |  |
Number Of Tenants Above Concentration Amount. | 0 | 0 | 0
Concentration Risk, Percentage | 10.00% | 10.00% | 10.00%
Maximum [Member] |  |  |
Future Minimum Rent [Line Items] |  |  |
Initial Term Lease Expiration Date | 2046 |  |

X
- Definition [Line Items] for Future Minimum Rent [Table] + References No definition available. + Details
Name: | bxp_FutureMinimumRentLineItems
Namespace Prefix: | bxp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Initial Term Lease Expiration Date + References No definition available. + Details
Name: | bxp_InitialTermLeaseExpirationDate
Namespace Prefix: | bxp_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Tenants Above Concentration Amount. + References No definition available. + Details
Name: | bxp_NumberOfTenantsAboveConcentrationAmount
Namespace Prefix: | bxp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |