Related Parties (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 property	Jun. 30, 2013	Dec. 31, 2013 property
Related Party Transaction [Line Items]
Net accounts receivable, related parties	$ 1,500,000		$ 1,500,000		$ 1,400,000
Accounts payable and accrued expenses, related parties	5,300,000		5,300,000		5,600,000
Management fees revenues, related parties	1,100,000	1,400,000	2,400,000	2,800,000
Ownership percentage in joint ventures					50.00%
Total assets	3,863,401,000		3,863,401,000		4,223,929,000
Debt, net	1,820,477,000		1,820,477,000
Increase in equity			11,015,000	0
Number of operating properties sold			5
Number of properties held for sale					8
Gain on sale of property			46,493,000	78,419,000
Hines [Member]
Related Party Transaction [Line Items]
Ownership percentage in joint ventures	30.00%		30.00%
Number of real estate properties	5		5		13
Total assets					172,900,000
Debt, net					11,100,000
Increase in equity			11,000,000
Number of operating properties sold			8
Gain on sale of property			23,300,000
Tenancy In Common [Member]
Related Party Transaction [Line Items]
Ownership percentage in joint ventures					10.00%
Number of real estate joint ventures					2
Gross proceeds, related parties					8,900,000
Consoldiated Real Estate Joint Ventures [Member]
Related Party Transaction [Line Items]
Number of real estate joint ventures					2
Unconsolidated Real Estate Joint Ventures [Member]
Related Party Transaction [Line Items]
Ownership percentage in joint ventures	50.00%		50.00%		51.00%
Total assets	$ 1,243,210,000		$ 1,243,210,000		$ 1,283,166,000
Number of operating properties sold					5
Number of real estate joint ventures					2