Stock Based Compensation (Outstanding Employee Stock Awards) (Details) - $ / shares		May 24, 2016	May 12, 2016	May 01, 2015	May 09, 2014	Jan. 03, 2014	Jun. 30, 2016	Dec. 31, 2015
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value							$ 19.75	$ 18.67
Unvested Shares							1,195,997	959,446
Deferred Stock Awards [Member] | Deferred Stock Award, Granted January 3, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]					87,706
Grant Date Fair Value						$ 16.45
Unvested Shares							62,004
Deferred Stock Awards [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 Awards [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 Awards [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 Awards [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 Awards [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 Awards [Member] | Deferred Stock Award, Granted May 9, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]				145,436
Grant Date Fair Value					$ 18.46
Unvested Shares							48,205
Deferred Stock Awards [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 Awards [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 Awards [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 Awards [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 Awards [Member] | Deferred Stock Award, Granted May 1, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]			244,283
Grant Date Fair Value				$ 17.59
Unvested Shares							143,652
Deferred Stock Awards [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 Awards [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 Awards [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 Awards [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%
Deferred Stock Awards [Member] | Deferred Stock Award, Granted May 12, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]		31,368
Grant Date Fair Value			$ 20.40
Unvested Shares							31,368
Deferred Stock Awards [Member] | Deferred Stock Award, Granted May 12, 2016 [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			100.00%
Deferred Stock Awards [Member] | Deferred Stock Award, Granted May 24, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]	260,335
Grant Date Fair Value		$ 19.91
Unvested Shares							214,916
Deferred Stock Awards [Member] | Deferred Stock Award, Granted May 24, 2016 [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 Awards [Member] | Deferred Stock Award, Granted May 24, 2016 [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 Awards [Member] | Deferred Stock Award, Granted May 24, 2016 [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 Awards [Member] | Deferred Stock Award, Granted May 24, 2016 [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 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]						227,074
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]						329,921
Performance Share Program Award [Member] | Performance Share Program Award, Granted May 24, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted	[1]	0
Grant Date Fair Value		$ 23.02
Unvested Shares	[2]						138,857

[1] Amounts reflect the total grant to employees and independent directors, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through June 30, 2016.

[2] Estimated based on Piedmont's cumulative TSR for the respective performance period through June 30, 2016. Share estimates are subject to change in future periods based on both Piedmont's and its peers' stock performance and dividends paid.