Debt (Details) (USD $)	12 Months Ended														0 Months Ended				0 Months Ended					12 Months Ended		0 Months Ended		12 Months Ended																																	12 Months Ended
	Dec. 31, 2013 period Debt_Facility		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2013 Interest Rate Swap [Member]	Dec. 31, 2013 Secured Debt [Member]		Dec. 31, 2012 Secured Debt [Member]		Dec. 31, 2013 Unsecured Debt [Member]		Dec. 31, 2012 Unsecured Debt [Member]		May 09, 2013 $350 Million Senior Notes [Member] Unsecured Debt [Member]	Dec. 31, 2013 $350 Million Senior Notes [Member] Unsecured Debt [Member]		Dec. 31, 2012 $350 Million Senior Notes [Member] Unsecured Debt [Member]	Dec. 18, 2013 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member]	Dec. 31, 2013 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member]	Dec. 31, 2012 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member]	Jan. 31, 2014 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] Subsequent Event [Member] agreement	Jan. 31, 2014 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] Interest Rate Swap [Member] Subsequent Event [Member]	Dec. 31, 2013 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] LIBOR [Member]		Dec. 18, 2013 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] Minimum [Member]	Dec. 18, 2013 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] Maximum [Member]	Dec. 31, 2013 Aon Center Chicago Mortgage Note [Member] Secured Debt [Member]	Dec. 31, 2013 $500 Million Unsecured Line of Credit [Member] Unsecured Debt [Member]		Dec. 31, 2012 $500 Million Unsecured Line of Credit [Member] Unsecured Debt [Member]		Dec. 31, 2013 $200.0 Million Mortgage Note [Member] Secured Debt [Member]		Dec. 31, 2012 $200.0 Million Mortgage Note [Member] Secured Debt [Member]	Dec. 31, 2013 $200.0 Million Mortgage Note [Member] Secured Debt [Member] Subsequent Event [Member]	Dec. 31, 2013 $25.0 Million Mortgage Note [Member] Secured Debt [Member]		Dec. 31, 2012 $25.0 Million Mortgage Note [Member] Secured Debt [Member]	Dec. 31, 2013 $25.0 Million Mortgage Note [Member] Secured Debt [Member] Subsequent Event [Member]	Dec. 31, 2013 $350.0 Million Secured Pooled Facility [Member] Secured Debt [Member] property		Dec. 31, 2012 $350.0 Million Secured Pooled Facility [Member] Secured Debt [Member]		Dec. 31, 2013 $105.0 Million Fixed-Rate Loan [Member] Secured Debt [Member]		Dec. 31, 2012 $105.0 Million Fixed-Rate Loan [Member] Secured Debt [Member]	Dec. 31, 2013 $125.0 Million Fixed-Rate Loan [Member] Secured Debt [Member] property		Dec. 31, 2012 $125.0 Million Fixed-Rate Loan [Member] Secured Debt [Member]		Dec. 31, 2013 $42.5 Million Fixed-Rate Loan [Member] Secured Debt [Member]		Dec. 31, 2012 $42.5 Million Fixed-Rate Loan [Member] Secured Debt [Member]	Dec. 31, 2013 $140 Million WDC Mortgage Notes [Member] Secured Debt [Member]		Dec. 31, 2012 $140 Million WDC Mortgage Notes [Member] Secured Debt [Member]	Dec. 31, 2013 $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member] Unsecured Debt [Member] agreement	Dec. 31, 2012 $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member] Unsecured Debt [Member]	Dec. 31, 2013 $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member] Unsecured Debt [Member] Interest Rate Swap [Member]	Dec. 31, 2013 $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member] Unsecured Debt [Member] LIBOR [Member]
Debt Instrument [Line Items]
Number of new debt facilities entered during the period	2
Debt instrument, face amount															$ 350,000,000	$ 350,000,000			$ 300,000,000	$ 300,000,000									$ 500,000,000				$ 200,000,000			$ 200,000,000	$ 25,000,000			$ 25,000,000	$ 350,000,000				$ 105,000,000			$ 125,000,000				$ 42,525,000.000			$ 140,000,000			$ 300,000,000
Rate																3.40%	[1],[2]												1.345%	[1],[3]			4.87%	[1]			5.70%	[1]			4.84%	[1],[4]			5.29%	[1]		5.50%	[1],[5]			5.70%	[1]		5.76%	[1]
Amount of repayments of debt																												225,000,000	75,000,000
Percentage of principal amount redeemed															100.00%
Maturity period																			5 years
Spread on variable rate																								1.20%	[1],[6]	0.00%	1.95%		1.175%																																1.45%	[1],[7]
Stated interest rate spread																				1.20%
Unencumbered interest coverage ratio																			1.75
Unencumbered leverage ratio																			1.60
Fixed charge coverage ratio																			1.50
Leverage ratio																			0.60
Secured debt ratio																			0.40
Net borrowings	237,000,000
Amount of indebtedness outstanding	2,002,205,000	[8]	1,416,525,000	[8]			987,525,000	[8]	987,525,000	[8]	1,014,680,000	[8]	429,000,000	[8]		348,680,000		0		0	0								366,000,000	[9]	129,000,000	[9]	200,000,000	[10]	200,000,000		25,000,000	[10]	25,000,000		350,000,000	[4]	350,000,000	[4]	105,000,000		105,000,000	125,000,000	[5]	125,000,000	[5]	42,525,000		42,525,000	140,000,000		140,000,000	300,000,000	300,000,000
Weighted average interest rate	3.80%	[1],[8]	4.30%	[1],[3]			5.17%	[1],[8]			2.46%	[1],[8]
Number of properties In collateralized pool																																									9							4
Effective rate																3.45%							2.79%																																					2.69%
LIBOR interest rate in effect																													0.17%
Additional extension period	1 year
Number of extension periods	2
Extension period	6 months
Number of interest rate swap agreements																						4																																				4
Notional Amount	530,000,000					580,000,000																	200,000,000																																			300,000,000
Interest payments on debt facilities	$ 69,800,000		$ 62,600,000		$ 66,700,000

[1] All of Piedmont’s outstanding debt as of December 31, 2013 and 2012 is interest-only debt.

[2] The $350 Million Senior Notes have a fixed coupon rate of 3.40%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 3.45%.

[3] 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 (1.175% as of December 31, 2013) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of December 31, 2013 consists of LIBOR draws at an average rate of 0.17% (subject to the additional spread mentioned above). Further, for the year ended December 31, 2013, Piedmont incurred net borrowings of approximately $237.0 million on its outstanding line of credit.

[4] Nine property collateralized pool includes:1200 Crown Colony Drive in Quincy, Massachusetts, Braker Pointe III in Austin, Texas, 2 Gatehall Drive in Parsippany, New Jersey, the One and Two Independence Square buildings in Washington, DC, 2120 West End Avenue in Nashville, Tennessee, 400 Bridgewater Crossing in Bridgewater, New Jersey, 200 Bridgewater Crossing in Bridgewater, New Jersey, and Fairway Center II in Brea, California.

[5] Four property collateralized pool includes 1430 Enclave Parkway in Houston, Texas, Windy Point I and II in Schaumburg, Illinois, and 1055 East Colorado Boulevard in Pasadena, California.

[6] On January 30, 2014, Piedmont drew the full commitment of the $300 Million Unsecured 2013 Term Loan. Additionally, Piedmont entered into four interest rate swap agreements with a total notional value of $200 million to effectively fix the interest rate for this portion of the debt at 2.79%.

[7] The $300 Million Unsecured 2011 Term Loan has a stated variable rate; however, Piedmont entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, the rate on this facility to 2.69% through maturity.

[8] Weighted average is based on the net book value of outstanding debt and interest rates in the table (or as footnoted) as of December 31, 2013.

[9] Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of August 21, 2017) provided Piedmont is not then in default and upon payment of extension fees.

[10] On January 31, 2014, Piedmont used the proceeds of the $300 Million Unsecured 2013 Term Loan mentioned above to fully repay the $200 Million Mortgage Note and the $25 Million Mortgage Note