Real Estate Investments Acquistions and Pro-Forma Information (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Business Acquisition [Line Items]
Real Estate and Accumulated Depreciation, Description of Property																	Total 2011		Total 2010	Total 2009
Real estate investment property, at cost	$ 2,406,783,000								$ 2,051,936,000								$ 2,406,783,000		$ 2,051,936,000
Real estate revenue	76,708,000	[1],[2]	71,931,000	[1],[2]	71,684,000	[1],[2]	69,204,000	[1],[2]	65,364,000	[1],[2]	65,032,000	[1],[2]	64,087,000	[1],[2]	64,007,000	[1],[2]	289,527,000		258,490,000	256,549,000
Land																	90,900,000		38,200,000	1,300,000
Buildings																	219,600,000		93,300,000	18,600,000
Tenant origination costs	15,700,000								9,100,000								15,700,000		9,100,000	0
Leasing commissions absorption costs	29,700,000								15,400,000								29,700,000		15,400,000	0
Net lease intangible assets	6,800,000								1,400,000								6,800,000		1,400,000	0
Net lease intangible liabilities	(2,500,000)								(1,500,000)								(2,500,000)		(1,500,000)	0
Fair value of assumed mortgage																	(78,500,000)		0	0
Total property purchase price																	281,700,000		155,900,000	19,900,000
Real estate revenues																	308,027,000		295,767,000
Income from continuing operations																	(1,701,000)		1,083,000
Net income																	104,311,000		37,517,000
Diluted earnings per share																	$ 1.57		$ 0.60
1140 Connecticut Avenue [Member]
Business Acquisition [Line Items]
Acquisition Date																	Jan 2011
1227 25th Street [Member]
Business Acquisition [Line Items]
Acquisition Date																	Mar 2011
Six Fifty North Glebe Road [Member]
Business Acquisition [Line Items]
Acquisition Date																	Jun 2011	[3]
Olney Village Center Member
Business Acquisition [Line Items]
Acquisition Date																	Aug 2011	[4]
Braddock Place Member
Business Acquisition [Line Items]
Acquisition Date																	Sep 2011
John Marshall II Member
Business Acquisition [Line Items]
Acquisition Date																	Sep 2011	[4]
1219 First Street [Member]
Business Acquisition [Line Items]
Acquisition Date																	Nov 2011	[3]
Gateway Overlook [Member]
Business Acquisition [Line Items]
Acquisition Date																	Dec 2010
Lansdowne Medical Office Building [Member]
Business Acquisition [Line Items]
Acquisition Date																	Aug 2009
Property Acquired Member
Business Acquisition [Line Items]
Square Footage Of Real Estate Property Acquired																	1,081,000		494,000,000	87,000,000
Real estate investment property, at cost	385,400,000								156,400,000								385,400,000		156,400,000	19,900,000
Property Acquired Member | 1140 Connecticut Avenue [Member]
Business Acquisition [Line Items]
Acquisition Date																	January 11, 2011
Real Estate and Accumulated Depreciation, Description of Property																	Office
Square Footage Of Real Estate Property Acquired																	184,000
Real estate investment property, at cost	80,250,000																80,250,000
Property Acquired Member | 1227 25th Street [Member]
Business Acquisition [Line Items]
Acquisition Date																	March 30, 2011
Real Estate and Accumulated Depreciation, Description of Property																	Office
Square Footage Of Real Estate Property Acquired																	130,000
Real estate investment property, at cost	47,000,000																47,000,000
Property Acquired Member | Six Fifty North Glebe Road [Member]
Business Acquisition [Line Items]
Acquisition Date																	June 15, 2011	[5]
Real Estate and Accumulated Depreciation, Description of Property																	Mutifamily	[5]
Real estate investment property, at cost	11,800,000	[5]															11,800,000	[5]
Property Acquired Member | Olney Village Center Member
Business Acquisition [Line Items]
Acquisition Date																	August 30, 2011
Real Estate and Accumulated Depreciation, Description of Property																	Retail
Square Footage Of Real Estate Property Acquired																	199,000
Real estate investment property, at cost	58,000,000																58,000,000
Property Acquired Member | Braddock Place Member
Business Acquisition [Line Items]
Acquisition Date																	September 13, 2011
Real Estate and Accumulated Depreciation, Description of Property																	Office
Square Footage Of Real Estate Property Acquired																	345,000
Real estate investment property, at cost	101,000,000																101,000,000
Property Acquired Member | John Marshall II Member
Business Acquisition [Line Items]
Acquisition Date																	September 15, 2011
Real Estate and Accumulated Depreciation, Description of Property																	Office
Square Footage Of Real Estate Property Acquired																	223,000
Real estate investment property, at cost	73,500,000																73,500,000
Property Acquired Member | Braddock Gateway [Member]
Business Acquisition [Line Items]
Acquisition Date																	November 23, 2011	[5]
Real Estate and Accumulated Depreciation, Description of Property																	Mutifamily	[5]
Property Acquired Member | 1219 First Street [Member]
Business Acquisition [Line Items]
Real estate investment property, at cost	13,850,000	[5]															13,850,000	[5]
Property Acquired Member | Nine Two Five and One Thousand Corporate Drive [Member]
Business Acquisition [Line Items]
Acquisition Date																			June 3, 2010
Real Estate and Accumulated Depreciation, Description of Property																			Office
Square Footage Of Real Estate Property Acquired																			271,000,000
Real estate investment property, at cost									68,000,000										68,000,000
Property Acquired Member | Gateway Overlook [Member]
Business Acquisition [Line Items]
Acquisition Date																			December 1, 2010
Real Estate and Accumulated Depreciation, Description of Property																			Retail
Square Footage Of Real Estate Property Acquired																			223,000,000
Real estate investment property, at cost									88,400,000										88,400,000
Property Acquired Member | Lansdowne Medical Office Building [Member]
Business Acquisition [Line Items]
Acquisition Date																				August 13, 2009
Real Estate and Accumulated Depreciation, Description of Property																				Medical Office
Square Footage Of Real Estate Property Acquired																				87,000,000
Real estate investment property, at cost																				19,900,000
Acquisition [Member]
Business Acquisition [Line Items]
Real estate revenue																	35,259,000		5,575,000
Net income																	$ 4,701,000		$ 1,460,000

[1] With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.

[2] The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

[3] As of December 31, 2011, WRIT had under development via joint venture arrangements, a mid-rise multifamily property in Arlington, Virginia (650 North Glebe) and a high-rise multifamily property in Alexandria, Virginia (1219 First Street). The total land value not yet placed into service of these development projects via joint venture arrangements at December 31, 2011 was $27.8 million.

[4] At December 31, 2011, our properties were encumbered by non-recourse mortgage amounts as follows: $35,399,000 on 3801 Connecticut Avenue, $16,531,000 on Walker House, $29,099,000 on Bethesda Hill, $36,097,000 on The Kenmore, $30,761,000 on West Gude Drive,$95,593,000 on 2445 M Street, $53,936,000 on John Marshall II, $42,997,000 on Prosperity Medical Center, $4,780,000 on 9707 Medical Center Drive, $7,974,000 on 15005 Shady Grove Road, $4,419,000 on Plum Tree Medical Center, $19,954,000 on Woodholme Medical Center, $4,597,000 on Ashburn Farm, $21,700,000 on Frederick Crossing, and $23,873,000 on Olney Village Center.

[5] Land for development