Investment in Unconsolidated Joint Ventures Income Statement of Unconsolidated Joint Ventures (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Operating Expenses	$ 82,226,000	$ 73,445,000	$ 67,047,000	$ 62,372,000	$ 100,407,000	$ 48,397,000	$ 44,813,000	$ 42,175,000	$ 285,090,000	$ 235,792,000	$ 156,382,000
Net Operating Income	(4,761,000)	(120,000)	5,576,000	5,793,000	(43,050,000)	7,570,000	5,692,000	4,492,000	6,488,000	(25,296,000)	(9,085,000)
Interest Expense	12,610,000	11,521,000	11,162,000	10,329,000	8,892,000	8,378,000	8,394,000	8,688,000	45,622,000	34,352,000	29,929,000
Depreciation and Amortization									118,031,000	74,626,000	49,120,000
Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Revenue									7,291
Operating Expenses									2,439
Net Operating Income									4,852
Interest Expense									1,814
Depreciation and Amortization									3,632
Net Income (Loss)									(594)
Equity Method Investee [Member] | US Airways Building [Member]
Schedule of Equity Method Investments [Line Items]
Revenue									2,560
Operating Expenses									0
Net Operating Income									2,560
Interest Expense									209
Depreciation and Amortization									1,219
Net Income (Loss)									1,132
Equity Method Investee [Member] | 7000 Central Park JV, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Revenue									1,136
Operating Expenses									778
Net Operating Income									358
Interest Expense									270
Depreciation and Amortization									836
Net Income (Loss)									(748)
Equity Method Investee [Member] | PKY CalSTRS Austin, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Revenue									3,595
Operating Expenses									1,661
Net Operating Income									1,934
Interest Expense									1,335
Depreciation and Amortization									1,577
Net Income (Loss)									$ (978)