Investments in Unconsolidated Companies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) entities	Dec. 31, 2017 USD ($) entities	Dec. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity in earnings of unconsolidated joint ventures	$ 21,444	$ 63,310	$ 47,403
Impairment charges	$ 0	4,481	$ 18,018
Number of unconsolidated joint ventures in which equity interests held | entities	8
Medical Office Portfolio Sale [Member]
Schedule of Equity Method Investments [Line Items]
Equity in earnings of unconsolidated joint ventures		$ 47,500
Number of unconsolidated joint ventures in which equity interests held | entities		2