Variable Interest Entities (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Eye Street 1201 N.W. Associates LLC [Member]
Variable Interest Entity [Line Items]
Piedmont’s % Ownership of Entity	49.50%
Net Carrying Amount	$ (8.5)	$ (7.4)
Variable interest entity, cash flow percent entitled to entity	100.00%
Eye Street 1225 N.W. Associates LLC [Member]
Variable Interest Entity [Line Items]
Piedmont’s % Ownership of Entity	49.50%
Net Carrying Amount	$ 9.3	3.8
Variable interest entity, cash flow percent entitled to entity	100.00%
Piedmont 500 W. Monroe Fee LLC [Member]
Variable Interest Entity [Line Items]
Piedmont’s % Ownership of Entity	100.00%
Net Carrying Amount	$ 252.1	$ 251.4
Variable interest entity, cash flow percent entitled to entity	100.00%