Stock Based Compensation (Outstanding Employee Deferred Stock Awards) (Details) - $ / shares		May. 01, 2015	May. 09, 2014	Jan. 03, 2014	Apr. 02, 2013	Nov. 07, 2012	Sep. 30, 2015	Dec. 31, 2014
Deferred Stock Award [Member] | Deferred Stock Award, Granted November 7, 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]					14,836
Grant Date Fair Value						$ 18.04
Unvested Shares							4,989
Deferred Stock Award [Member] | Deferred Stock Award, Granted November 7, 2012 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted November 7, 2012 [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted November 7, 2012 [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted November 7, 2012 [Member] | Share-based Compensation Award, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted April 2, 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]				118,174
Grant Date Fair Value					$ 19.47
Unvested Shares							37,084
Deferred Stock Award [Member] | Deferred Stock Award, Granted April 2, 2013 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted April 2, 2013 [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted April 2, 2013 [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted April 2, 2013 [Member] | Share-based Compensation Award, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]			95,476
Grant Date Fair Value				$ 16.45
Unvested Shares							82,673
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member] | Share-based Compensation Award, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted January 3, 2014 [Member] | Share-based Compensation Award, Tranche Five [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 9, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]		163,222
Grant Date Fair Value			$ 18.47
Unvested Shares							96,032
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 9, 2014 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 9, 2014 [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 9, 2014 [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 9, 2014 [Member] | Share-based Compensation Award, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 1, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]	271,970
Grant Date Fair Value		$ 17.59
Unvested Shares							219,403
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 1, 2015 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 1, 2015 [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 1, 2015 [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Award [Member] | Deferred Stock Award, Granted May 1, 2015 [Member] | Share-based Compensation Award, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Performance Share Program Award [Member] | Performance Share Program Award, Granted April 2, 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]				0
Grant Date Fair Value					$ 18.91
Unvested Shares	[2]						53,287
Performance Share Program Award [Member] | Performance Share Program Award, Granted May 9, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]		0
Grant Date Fair Value			$ 22.00
Unvested Shares	[2]						159,271
Performance Share Program Award [Member] | Performance Share Program Award, Granted May 1, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]	0
Grant Date Fair Value		$ 18.42
Unvested Shares	[2]						302,422
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value							$ 17.88	$ 18.12
Unvested Shares							955,161	506,404

[1] Amounts reflect the total grant to employees, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2015.

[2] Estimated based on Piedmont's cumulative TSR for the respective performance period through September 30, 2015. Share estimates are subject to change in future periods based on both Piedmont's and its peers' stock performance and dividends paid.