Summary of Significant Accounting Policies Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from External Customer
Revenues	$ 383,718	$ 551,478	$ 867,647	$ 999,134
Leasing and other commissions
Revenue from External Customer
Revenues	120,079	217,381	260,517	389,852
Capital markets commissions
Revenue from External Customer
Revenues	52,959	128,750	180,882	231,547
Gains from mortgage banking activities/originations, net
Revenue from External Customer
Revenues	69,071	45,091	119,494	76,437
Management services, servicing fees and other
Revenue from External Customer
Revenues	$ 141,609	$ 160,256	$ 306,754	$ 301,298