Debt (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended		6 Months Ended												6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Forward Starting Interest Rate Swap [Member] contract	Jun. 30, 2014 Unsecured Debt [Member] Unsecured 300 million 2013 Term Loan Maturing 2019 [Member]	Jun. 30, 2014 Unsecured Debt [Member] $500 Million Unsecured Line of Credit [Member]	Jun. 30, 2014 Secured Debt [Member] Mortgage Note $200 Million [Member]		Jun. 30, 2014 Secured Debt [Member] Mortgage Note $25 Million [Member]		Jun. 30, 2014 Secured Debt [Member] Secured Pooled Facility [Member]		Dec. 31, 2013 Secured Debt [Member] Secured Pooled Facility [Member]	Jun. 30, 2014 Secured Debt [Member] Mortgage Loan Maturing September 1, 2021 [Member]		Jun. 27, 2014 Secured Debt [Member] Mortgage Loan Maturing September 1, 2021 [Member]	Jun. 27, 2014 Secured Debt [Member] Mortgage Loan Maturing September 1, 2021 [Member] The 5 Wall Street Building [Member]	Jun. 30, 2014 Senior Notes [Member] 2014 Senior Notes [Member] contract		Jun. 30, 2014 Senior Notes [Member] 2014 Senior Notes [Member] Forward Starting Interest Rate Swap [Member]
Debt Instrument [Line Items]
Face amount of debt instrument							$ 300,000,000	$ 500,000,000	$ 200,000,000		$ 25,000,000		$ 350,000,000		$ 350,000,000	$ 35,000,000		$ 35,000,000.0	$ 35,000,000	$ 400,000,000
Borrowing capacity of line of credit								500,000,000
Rate									4.87%	[1]	5.70%	[1]	4.84%	[1],[2]		5.55%	[1],[3]			4.45%	[1],[4]
Proceeds from debt																				399,200,000
Unsecured debt- discount on debt	4,592,000		4,592,000		1,320,000															800,000
Term of notes																				10 years
Number of swaps settled						5														5
Total notional value	500,000,000		500,000,000				200,000,000															350,000,000
Settlement of forward starting interest rate swaps			(14,960,000)	(672,000)																15,000,000
Mortgage loan assumed																			33,700,000
Premium from estimated fair market value adjustment of mortgage loan assumed	3,499,000		3,499,000		0											3,500,000
Net borrowings								188,000,000
Repayments								242,000,000
Interest payments on debt facilities	16,700,000	16,100,000	33,200,000	31,800,000
Capitalized interest	$ 500,000	$ 0	$ 800,000	$ 0

[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] 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%.

[4] 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%.