Commitments and Contingencies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) obligation	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of outstanding letters of credit | obligation		13
Outstanding letter of credit		$ 47,180
Outstanding construction financings for leased properties		507,931	$ 194,365
Additional financing to complete construction		446,633
Agreement to acquire outpatient medical facilities		261,000
Total contingent purchase obligations		$ 19,925
Expense recognized for the donation of the corporate headquarters	$ 40,730