Segment Information (Other Segment - NOI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Information
NOI	$ 346,241	$ 383,877	$ 1,132,442	$ 1,119,555
Operating Segments | Other
Segment Information
NOI	66,197	137,289	320,108	403,240
Investment income and other, net	5,910	6,871	24,079	19,317
Operating results	692	1,906	4,282	4,894
Total of certain items that impact NOI	16,263	77,380	172,385	244,517
Income from mark-to-market income (loss) of investments in our deferred compensation plan	1,975	204	5,233	2,625
Operating Segments | Other | JBGS
Segment Information
Operating results	12,971	72,919	160,634	233,310
Operating Segments | Other | Real estate investment
Segment Information
NOI	49,934	59,909	147,723	158,723
Operating Segments | Other | Real estate investment | The Mart and trade shows
Segment Information
NOI	25,422	21,758	74,859	70,914
Operating Segments | Other | Real estate investment | 555 California Street
Segment Information
NOI	11,013	9,899	33,647	24,010
Operating Segments | Other | Real estate investment | Other investments
Segment Information
NOI	7,589	21,381	15,138	44,482
Investment income and other, net	5,910	6,871	24,079	19,317
Operating Segments | Other | Real estate fund investments
Segment Information
Operating results	$ 2,600	$ 2,555	$ 7,469	$ 6,313