Income Taxes (Tax Effects of Temporary Differences and Carryforwards Included in Net Deferred Tax Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Property, primarily differences in depreciation and amortization, the tax basis of land assets and the treatment of interests and certain costs	$ (409,803)	$ (413,566)	$ (406,023)
Operating loss and interest deduction carryforwards	589,326	564,091	398,859
Expense accruals and other	18,185	14,624	15,355
Valuation allowance	(514,349)	(503,531)	(352,528)
Net deferred tax liabilities	(316,641)	(338,382)	(344,337)
Increase (decrease) in net deferred tax liability	(21,700)	(6,000)
Operating loss carryforwards, Valuation allowance	379,500	369,400	251,100
Net difference between tax bases and the reported amount of REIT assets and liabilities	$ 4,400,000	4,700,000
Period during which subject built-in gains tax (in years)	5 years
NOL carryforward related to TRS entities	$ 490,400
NOL carryforward related to REIT	1,100,000
TRSs
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Operating loss carryforwards, Valuation allowance	84,700	85,500	$ 66,100
Life Sciences Acquisitions
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Net deferred tax liability	9,400
HCT, UK, Ardent
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Net deferred tax liability		51,800
HCT
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
Net deferred tax liability		$ 32,300
NOL carryforward related to REIT	18,600
Ardent
Tax effects of temporary differences and carryforwards included in the net deferred tax liabilities
NOL carryforward related to REIT	397,900
Tax credit carryforward, amount	$ 10,500