Other Real Estate Property Investments - Consideration (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Other real estate acquisitions
Consideration, Cash Paid	$ 503,470,000
Consideration, Debt and Other Liabilities Assumed	37,278,000
Consideration, Noncontrolling Interest	6,321,000
Assets Acquired, Real Estate	483,046,000
Assets Acquired, Net Intangibles	64,023,000
Senior housing
Acquisition
Acquisition of facility		18,000,000
Price paid upon exercise of purchase option		16,000,000
Other real estate acquisitions
Consideration, Cash Paid	233,797,000
Consideration, Debt and Other Liabilities Assumed	3,351,000
Consideration, Noncontrolling Interest	6,321,000
Assets Acquired, Real Estate	215,255,000
Assets Acquired, Net Intangibles	28,214,000
Consideration to non-managing member limited liability company units	5,000,000
Post-acute/skilled
Acquisition
Acquisition of facility		400,000
Land acquired (in acres)		38
Life science
Other real estate acquisitions
Consideration, Cash Paid	43,500,000
Consideration, Debt and Other Liabilities Assumed	250,000
Assets Acquired, Real Estate	41,281,000
Assets Acquired, Net Intangibles	2,469,000
Medical office
Other real estate acquisitions
Consideration, Cash Paid	226,173,000
Consideration, Debt and Other Liabilities Assumed	33,677,000
Assets Acquired, Real Estate	226,510,000
Assets Acquired, Net Intangibles	33,340,000
Senior housing, life science and medical office
Other real estate acquisitions
Payments to acquire productive assets	$ 273,000,000	$ 173,000,000