Real Estate Facilities (Summary Of The Assets Acquired And Liabilities Assumed) (Details) (USD $) In Thousands	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Above-market in-place lease value	$ 543
Below-market in-place lease value	(56)
Total purchase price	26,802
Net operating assets acquired and liabilities assumed	(189)
Total cash paid	26,613	123,582
Land [Member]
Land	6,447
Buildings And Equipment [Member]
Buildings and equipment	$ 19,868

The contractual purchases price of the real estate acquired net of credit for committed transaction costs.

Name:	psb_ContractualPurchasePriceOfRealEstateNetOfTransactionCostsCredit
Namespace Prefix:	psb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the identifiable intangible liability established upon acquisition based on an unfavorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date.

+ Details

Name:	psb_FiniteLivedIntangibleLiabilityOffMarketLeaseUnfavorableGross
Namespace Prefix:	psb
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of acquisition cost of real estate acquired allocated to net operating assets and liabilities.

+ Details

Name:	psb_NetOperatingAssetsAcquiredAndLiabiltiesAssumed
Namespace Prefix:	psb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Real Estate Acquisition, Purchase Price Allocation, Building and Equipment.

+ Details

Name:	psb_RealEstateAcquisitionPurchasePriceAllocationBuildingAndEquipment
Namespace Prefix:	psb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Real Estate Acquisition, Purchase Price Allocation, Land.

+ Details

Name:	psb_RealEstateAcquisitionPurchasePriceAllocationLand
Namespace Prefix:	psb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the identifiable intangible asset established upon acquisition based on a favorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 37

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetOffMarketLeaseFavorableGross
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow from the acquisition of a piece of land, anything permanently fixed to it, including buildings, structures on it and so forth; includes real estate intended to generate income for the owner; excludes real estate acquired for use by the owner.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 17

+ Details

Name:	us-gaap_PaymentsToAcquireRealEstate
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration