Debt (Narrative) (Details) (USD $)	3 Months Ended					16 Months Ended									3 Months Ended																		0 Months Ended				3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013		Mar. 06, 2014 Forward Starting Interest Rate Swap [Member] contract	Mar. 31, 2014 Unsecured Debt [Member]		Dec. 31, 2013 Unsecured Debt [Member]		Mar. 31, 2014 Unsecured Debt [Member] Unsecured 300 million 2013 Term Loan Maturing 2019 [Member]	Dec. 31, 2013 Unsecured Debt [Member] Unsecured 300 million 2013 Term Loan Maturing 2019 [Member]	Mar. 31, 2014 Unsecured Debt [Member] $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member]	Dec. 31, 2013 Unsecured Debt [Member] $300 Million 2011 Unsecured Term Loan Maturing 2016 [Member]	Mar. 31, 2014 Unsecured Debt [Member] $500 Million Unsecured Line of Credit [Member]		Dec. 31, 2013 Unsecured Debt [Member] $500 Million Unsecured Line of Credit [Member]		Mar. 31, 2014 Secured Debt [Member]		Dec. 31, 2013 Secured Debt [Member]		Mar. 31, 2014 Secured Debt [Member] Mortgage Note $200 Million [Member]		Dec. 31, 2013 Secured Debt [Member] Mortgage Note $200 Million [Member]	Mar. 31, 2014 Secured Debt [Member] Mortgage Note $25 Million [Member]		Dec. 31, 2013 Secured Debt [Member] Mortgage Note $25 Million [Member]	Mar. 31, 2014 Secured Debt [Member] Secured Pooled Facility [Member]		Mar. 06, 2014 Secured Debt [Member] Secured Pooled Facility [Member]	Dec. 31, 2013 Secured Debt [Member] Secured Pooled Facility [Member]	Mar. 06, 2014 Senior Notes [Member] 2014 Senior Notes [Member] contract		Mar. 31, 2014 Senior Notes [Member] 2014 Senior Notes [Member]	Dec. 31, 2013 Senior Notes [Member] 2014 Senior Notes [Member]	Mar. 31, 2014 Senior Notes [Member] 2014 Senior Notes [Member] Prior to December 15, 2023 [Member]	Mar. 31, 2014 Senior Notes [Member] 2014 Senior Notes [Member] On or after December 15, 2023 [Member]	Mar. 06, 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		$ 300,000,000		$ 500,000,000								$ 200,000,000			$ 25,000,000			$ 350,000,000				$ 400,000,000		$ 400,000,000
Borrowing capacity of line of credit															500,000,000
Total notional value	500,000,000										200,000,000		300,000,000																										350,000,000
Rate																							4.87%	[1]		5.70%	[1]		4.84%	[1],[2]			4.45%	[1],[3]
Proceeds from debt																																	399,200,000
Discount on debt	4,703,000			1,320,000																													800,000
Term of notes																																	10 years
Number of swaps settled						5																											5
Settlement of forward starting interest rate swaps	(14,960,000)		0																														15,000,000
Amount Outstanding	2,029,822,000	[4]		2,002,205,000	[4]		1,617,297,000	[4]	1,014,680,000	[4]	300,000,000	0	300,000,000	300,000,000	272,000,000	[5]	366,000,000	[5]	412,525,000	[4]	987,525,000	[4]	0		200,000,000	0		25,000,000	0		350,000,000	350,000,000			396,587,000	0
Percentage of principal amount that may be redeemed																																					100.00%	100.00%
Net borrowings															68,000,000
Repayments															162,000,000
Interest payments on debt facilities	16,100,000		15,700,000
Capitalized interest	$ 400,000		$ 0

[1] All of Piedmont’s outstanding debt as of March 31, 2014 and December 31, 2013 was interest-only debt.

[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 $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%.

[4] Weighted average is based on contractual balance of outstanding debt and interest rates in the table as of March 31, 2014.

[5] 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.