Variable Interest Entities (Summary Of Consolidated Variable Interest Entities) (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) joint_venture	Dec. 31, 2016 USD ($) joint_venture
Variable Interest Entity [Line Items]
Assets to longer considered VIEs		$ 249,500
Number of VIE real estate joint ventures guaranteed by company | joint_venture	1	1
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Assets Held by VIEs	$ 236,830	$ 504,293
Assets Held as Collateral for Debt	42,552	46,136
Maximum Risk of Loss	$ 29,784	$ 29,784