Acquisitions and Dispositions (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) buildings	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) buildings	Jun. 30, 2015 USD ($)
Number Of Real Estate Properties Acquired | buildings	2		2
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			8 years 10 months 24 days
Operating Leases, Income Statement, Lease Revenue	$ 200,520,000	$ 201,996,000	$ 402,323,000	$ 416,611,000
Operating Income (Loss)	148,766,000	181,266,000	227,924,000	269,466,000
Property, Plant, and Equipment, Fair Value Disclosure	72,824,000		72,824,000
Gain on dissolution of unconsolidated company	30,697,000	0	30,697,000	0
Promote income	$ 24,087,000	$ 0	$ 24,087,000	$ 0
Duke Realty Limited Partnership [Member]
Number Of Real Estate Properties Acquired | buildings	1		1
Property, Plant, and Equipment, Fair Value Disclosure	$ 63,000,000		$ 63,000,000
Proceeds from Equity Method Investment, Dividends or Distributions			2,760,000
Equity Method Investments	$ (35,063,000)		(35,063,000)
Gain on dissolution of unconsolidated company			30,697,000
Other 2016 Acquisitions [Member]
Operating Leases, Income Statement, Lease Revenue			364,000
Operating Income (Loss)			$ 89,000
Gramercy Property Trust [Member]
Number of Real Estate Properties | buildings	7		7
Duke/Hulfish LLC [Member]
Number of Real Estate Properties | buildings	8		8
Duke/Hulfish LLC [Member]
Equity Method Investment, Ownership Percentage	20.00%		20.00%