Line of Credit and Notes Payable (Details) (USD $)	3 Months Ended			9 Months Ended																																3 Months Ended			3 Months Ended			3 Months Ended			4 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010	Dec. 31, 2010	Sep. 30, 2011 Minimum [Member] Unsecured Debt [Member] Unsecured $500 Million Facility [Member]	Sep. 30, 2011 Unsecured Debt [Member] Unsecured $500 Million Facility [Member] Maximum [Member]	Sep. 30, 2011 Secured Debt [Member] Fixed-Rate $45 Million Loan [Member]		Dec. 31, 2010 Secured Debt [Member] Fixed-Rate $45 Million Loan [Member]	Sep. 30, 2011 Secured Debt [Member] Mortgage Note $200 Million [Member]		Dec. 31, 2010 Secured Debt [Member] Mortgage Note $200 Million [Member]	Sep. 30, 2011 Secured Debt [Member] Mortgage Note $25 Million [Member]		Dec. 31, 2010 Secured Debt [Member] Mortgage Note $25 Million [Member]	Sep. 30, 2011 Secured Debt [Member] Secured Pooled Facility [Member]		Dec. 31, 2010 Secured Debt [Member] Secured Pooled Facility [Member]		Sep. 30, 2011 Secured Debt [Member] Fixed-Rate $105 Million Loan [Member]		Dec. 31, 2010 Secured Debt [Member] Fixed-Rate $105 Million Loan [Member]	Sep. 30, 2011 Secured Debt [Member] Fixed-Rate $125 Million Loan [Member]		Dec. 31, 2010 Secured Debt [Member] Fixed-Rate $125 Million Loan [Member]		Sep. 30, 2011 Secured Debt [Member] Fixed-Rate $42.5 Million Loan [Member]		Dec. 31, 2010 Secured Debt [Member] Fixed-Rate $42.5 Million Loan [Member]	Sep. 30, 2011 Secured Debt [Member] WDC Mortgage Notes $140 Million[Member]		Dec. 31, 2010 Secured Debt [Member] WDC Mortgage Notes $140 Million[Member]	Sep. 30, 2011 Secured Debt [Member] 500 W. Monroe Mortgage Loan $140 Million [Member]		Dec. 31, 2010 Secured Debt [Member] 500 W. Monroe Mortgage Loan $140 Million [Member]	Sep. 30, 2011 Secured Debt [Member] 500 W. Monroe Mezzanine I Loan- A Participation $45 Million [Member]		Dec. 31, 2010 Secured Debt [Member] 500 W. Monroe Mezzanine I Loan- A Participation $45 Million [Member]	Jun. 27, 2011 Unsecured Debt [Member] Unsecured $250 Million Term Loan [Member]	Sep. 30, 2011 Unsecured Debt [Member] Unsecured $250 Million Term Loan [Member]	Dec. 31, 2010 Unsecured Debt [Member] Unsecured $250 Million Term Loan [Member]	Sep. 30, 2011 Unsecured Debt [Member] Unsecured $500 Million Facility [Member]		Dec. 31, 2010 Unsecured Debt [Member] Unsecured $500 Million Facility [Member]	Sep. 30, 2011 Secured Debt [Member]		Dec. 31, 2010 Secured Debt [Member]	Sep. 30, 2011 Unsecured Debt [Member]		Dec. 31, 2010 Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount										$ 45,000,000			$ 200,000,000			$ 25,000,000			$ 350,000,000				$ 105,000,000			$ 125,000,000				$ 42,500,000			$ 140,000,000			$ 140,000,000			$ 45,000,000			$ 250,000,000			$ 500,000,000
Line Of Credit Facility Extension Period																																													1 year
Interest Payments on Debt Facilities	16,800,000		16,700,000	50,100,000		53,000,000
Rate										5.20%	[1]		4.87%	[1]		5.70%	[1]		4.84%	[1],[2]			5.29%	[1]		5.50%	[1],[3]			5.70%	[1]		5.76%	[1]											0.84%	[1],[4]
Debt, Weighted Average Interest Rate	3.89%			3.89%																																												4.63%			0.84%	[1],[5]
Debt Weighted Average Interest Rate Excluding Discontinued Operation	3.79%	[1],[5]		3.79%	[1],[5]																																											4.59%	[1],[5]
Line of credit and notes payable, outstanding	$ 1,544,525,000			$ 1,544,525,000			$ 1,282,525,000			$ 45,000,000		$ 45,000,000	$ 200,000,000		$ 200,000,000	$ 25,000,000		$ 25,000,000	$ 350,000,000	[2]	$ 350,000,000	[2]	$ 105,000,000		$ 105,000,000	$ 125,000,000	[3]	$ 125,000,000	[3]	$ 42,525,000		$ 42,525,000	$ 140,000,000		$ 140,000,000	$ 140,000,000			$ 45,000,000					$ 250,000,000	$ 327,000,000			$ 1,217,525,000		$ 1,032,525,000	$ 327,000,000		$ 250,000,000
Derivative, Cap Interest Rate																																				2.19%			2.19%
Debt Instrument, Basis Spread on Variable Rate																																				1.008%	[6]		1.45%	[6]		1.50%			0.475%
LIBOR Interest Rate In Effect								0.23%	0.24%
Debt Instrument, Description of Variable Rate Basis																																				LIBOR			LIBOR			LIBOR
Prime Rate In Effect	3.25%			3.25%

[1] All of Piedmont’s outstanding debt as of September 30, 2011 and December 31, 2010 is interest-only debt.

[2] Nine property collateralized pool includes: 1200 Crown Colony Drive, Braker Pointe III, 2 Gatehall Drive, One and Two Independence Square, 2120 West End Avenue, 400 Bridgewater Crossing, 200 Bridgewater Crossing, and Fairway Center II.

[3] Four property collateralized pool includes 1430 Enclave Parkway, Windy Point I and II, and 1055 East Colorado Boulevard.

[4] Piedmont may select from multiple interest rate options with each draw, including the prime rate and various-length LIBOR locks. All LIBOR selections are subject to an additional spread (0.475% as of September 30, 2011) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of September 30, 2011 consisted of several LIBOR draws ranging between 0.23% and 0.24% (subject to the additional spread mentioned above) as well as a draw subject to the prime rate which was 3.25% at that time.

[5] Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of September 30, 2011. As such, the following metrics would change to 4.63% for the weighted average interest rate of secured debt, and 3.89% for the weighted average interest rate of all outstanding debt if the note payable included in the disposal group of assets and liabilities held for sale (related to the 35 W. Wacker Building) was included in the calculations.

[6] Subject to interest rate cap agreements, which limit Piedmont’s exposure to potential increases in the LIBOR rate to 2.19%.