Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Total revenue		$ 752,556		$ 725,767
Expenses
Transaction costs		615		460
Depreciation and amortization		171,094		164,594
Total expenses		481,187		475,591
Other income (expense)
Interest expense		(101,591)		(101,009)
Net income		577,146		131,159
Income (loss) from unconsolidated joint ventures		(369)		213
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenue	[1]	93,203		82,955
Expenses
Operating		35,401		30,499
Depreciation and amortization		32,035		28,646
Total expenses		67,436		59,145
Other income (expense)
Interest expense		(22,583)		(20,757)
Net income		3,184		3,053
Company's share of net income		1,252		1,584
Basis differential	[3]	(1,621)	[2]	(1,371)
Income (loss) from unconsolidated joint ventures		(369)		213
Straight-line rent adjustments		9,700		5,800
Colorado Center [Member]
Other income (expense)
Straight-line rent adjustments		500		500
Above and below market rent adjustments, net		$ 300		$ 400

[1] Includes straight-line rent adjustments of approximately $9.7 million and $5.8 million for the three months ended March 31, 2020 and 2019, respectively.

[2] Includes straight-line rent adjustments of approximately $0.5 million and $0.5 million for the three months ended March 31, 2020 and 2019, respectively. Also includes net above-/below-market rent adjustments of approximately $0.3 million and $0.4 million for the three months ended March 31, 2020 and 2019, respectively.

[3] Includes straight-line rent adjustments of approximately $0.5 million and $0.5 million for the three months ended March 31, 2020 and 2019, respectively. Also includes net above-/below-market rent adjustments of approximately $0.3 million and $0.4 million for the three months ended March 31, 2020 and 2019, respectively.