Debt (Details) (USD $)	6 Months Ended																																					6 Months Ended								6 Months Ended				6 Months Ended
	Jun. 30, 2014 period		Dec. 31, 2013		Jun. 30, 2014 Secured Debt [Member]		Dec. 31, 2013 Secured Debt [Member]		Jun. 30, 2014 Unsecured Debt [Member]		Dec. 31, 2013 Unsecured Debt [Member]		Jun. 30, 2014 Mortgage Note $200 Million [Member] Secured Debt [Member]		Dec. 31, 2013 Mortgage Note $200 Million [Member] Secured Debt [Member]	Jun. 30, 2014 Mortgage Note $25 Million [Member] Secured Debt [Member]		Dec. 31, 2013 Mortgage Note $25 Million [Member] Secured Debt [Member]	Jun. 30, 2014 Secured Pooled Facility [Member] Secured Debt [Member] property		Dec. 31, 2013 Secured Pooled Facility [Member] Secured Debt [Member]	Jun. 30, 2014 Fixed-Rate $105 Million Loan [Member] Secured Debt [Member]		Dec. 31, 2013 Fixed-Rate $105 Million Loan [Member] Secured Debt [Member]	Jun. 30, 2014 Fixed-Rate $125 Million Loan [Member] Secured Debt [Member] property		Dec. 31, 2013 Fixed-Rate $125 Million Loan [Member] Secured Debt [Member]	Jun. 30, 2014 Fixed-Rate $42.5 Million Loan [Member] Secured Debt [Member]		Dec. 31, 2013 Fixed-Rate $42.5 Million Loan [Member] Secured Debt [Member]	Jun. 30, 2014 WDC Mortgage Notes $140 Million[Member] Secured Debt [Member]		Dec. 31, 2013 WDC Mortgage Notes $140 Million[Member] Secured Debt [Member]	Jun. 30, 2014 Mortgage Loan Maturing September 1, 2021 [Member] Secured Debt [Member]		Jun. 27, 2014 Mortgage Loan Maturing September 1, 2021 [Member] Secured Debt [Member]	Dec. 31, 2013 Mortgage Loan Maturing September 1, 2021 [Member] Secured Debt [Member]	Jun. 30, 2014 $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]	Jun. 30, 2014 $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member] Unsecured Debt [Member] Interest Rate Swap [Member]	Jun. 30, 2014 $500 Million Unsecured Line of Credit [Member] Unsecured Debt [Member]		Dec. 31, 2013 $500 Million Unsecured Line of Credit [Member] Unsecured Debt [Member]		Jun. 30, 2014 $500 Million Unsecured Line of Credit [Member] Unsecured Debt [Member] LIBOR [Member]	Jun. 30, 2014 $350 Million Senior Notes [Member] Senior Notes [Member]		Dec. 31, 2013 $350 Million Senior Notes [Member] Senior Notes [Member]	Jun. 30, 2014 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]	Jun. 30, 2014 Unsecured 300 million 2013 Term Loan Maturing 2019 [Member] Unsecured Debt [Member] Interest Rate Swap [Member]	Jun. 30, 2014 2014 Senior Notes [Member] Senior Notes [Member]		Dec. 31, 2013 2014 Senior Notes [Member] Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of debt instrument													$ 200,000,000			$ 25,000,000			$ 350,000,000		$ 350,000,000	$ 105,000,000			$ 125,000,000			$ 42,500,000.0			$ 140,000,000			$ 35,000,000		$ 35,000,000.0		$ 300,000,000				$ 500,000,000					$ 350,000,000			$ 300,000,000				$ 400,000,000
Borrowing capacity of line of credit																																										500,000,000
Rate													4.87%	[1]		5.70%	[1]		4.84%	[1],[2]		5.29%	[1]		5.50%	[1],[3]		5.70%	[1]		5.76%	[1]		5.55%	[1],[4]												3.40%	[1],[5]						4.45%	[1],[6]
Weighted Average Rate	3.49%	[1],[7]			5.55%	[1],[7]			2.94%	[1],[7]
Line of credit, effective interest rate																																										1.34%	[1],[8]
Amount Outstanding	2,107,085,000	[7]	2,002,205,000	[7]	449,677,000	[7]	987,525,000	[7]	1,657,408,000	[7]	1,014,680,000	[7]	0		200,000,000	0		25,000,000	0		350,000,000	105,000,000		105,000,000	125,000,000		125,000,000	42,525,000		42,525,000	140,000,000		140,000,000	37,152,000			0	300,000,000		300,000,000		312,000,000	[9]	366,000,000	[9]		348,741,000		348,680,000	300,000,000		0		396,667,000		0
Number of properties in collateralized pool																			9						4
Effective interest rate																																		3.75%							2.69%						3.45%						2.79%	4.48%
Basis spread on variable rate																																						1.45%	[1],[10]							1.175%				1.20%	[1],[11]
LIBOR rate in effect																																										0.16%
Maximum extension period	1 year
Number of extension periods	2
Extension period	6 months
Effective interest rate																																															3.43%							4.10%
Total notional value	$ 500,000,000																																					$ 300,000,000												$ 200,000,000

[1] All of Piedmont’s outstanding debt as of June 30, 2014 and December 31, 2013 was interest-only debt, except for the amortizing mortgage loan assumed in conjunction with the purchase of the 5 Wall Street building.

[2] Nine property collateralized pool, which was repaid in full on March 7, 2014, included: 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] The $35 Million Mortgage Note has a fixed rate of 5.55%, however, upon acquiring the mortgage note, it was marked to estimated fair value resulting in an effective interest rate of 3.75%.

[5] 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%. After consideration of the impact of settled interest rate swap agreements, in addition to the issuance discount, the effective interest rate on this debt is 3.43%.

[6] The $400 Million Senior Notes have a fixed coupon rate of 4.45%, however, as a result of the issuance of the notes at a discount, Piedmont recognizes an effective interest rate on this debt issuance of 4.48%. After consideration of the impact of settled interest rate swap agreements, in addition to the issuance discount, the effective interest rate on this debt is 4.10%.

[7] Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of June 30, 2014.

[8] 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 June 30, 2014) over the selected rate based on Piedmont’s current credit rating. The outstanding balance as of June 30, 2014 consisted of 30-day LIBOR draws at a rate of 0.16% (subject to the additional spread mentioned above).

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

[11] The $300 Million Unsecured 2013 Term Loan has a stated variable rate; however, Piedmont entered into interest rate swap agreements which effectively fix, absent any changes to Piedmont's credit rating, the rate for $200 million of the loan amount to 2.79% .