Segment Reporting Segment Reporting (Second Generation Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	$ 61,900	$ 98,821	$ 91,798
Operating Segments [Member]
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	61,900	98,821	91,798
Operating Segments [Member] | Industrial [Member]
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	45,716	53,840	41,971
Operating Segments [Member] | Medical Office [Member]
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	4,711	3,131	3,106
Operating Segments [Member] | Office Building [Member]
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	11,443	41,124	46,600
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Payments For Second Generation Tenant Improvements Leasing Costs And Building Improvements	$ 30	$ 726	$ 121