Washington Real Estate Investment Trust Annual report pursuant to Section 13 and 15(d)

Accounting Policies Fair value of in place leases (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Tenant Origination Costs Member
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 56,327	$ 47,697
Finite-Lived Intangible Assets, Accumulated Amortization	35,463	29,653
Finite-Lived Intangible Assets, Net	20,864	18,044
Leasing Commissions Absorption Costs Member
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	93,729	78,629
Finite-Lived Intangible Assets, Accumulated Amortization	60,289	48,376
Finite-Lived Intangible Assets, Net	33,440	30,253
Net Lease Intangible Assets Member
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	19,724	12,495
Finite-Lived Intangible Assets, Accumulated Amortization	9,495	7,008
Finite-Lived Intangible Assets, Net	10,229	5,487
Net Lease Intangible Liabilities Member
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Liabilities, Net Lease, Gross	34,027	26,348
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	20,974	19,403
Finite-lived Intangible Liabilities, Net Lease, Net	13,053	6,945
Leases, Acquired-in-Place, Below-Market Ground Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	12,080	12,080
Finite-Lived Intangible Assets, Accumulated Amortization	1,335	1,145
Finite-Lived Intangible Assets, Net	$ 10,745	$ 10,935