Acquisitions of Real Estate Property (Details) $ / shares in Units, $ in Thousands, CAD in Millions		1 Months Ended				3 Months Ended								12 Months Ended
	Aug. 04, 2015 USD ($) property	Aug. 31, 2015 property	Jan. 31, 2015 USD ($) property $ / shares shares	Sep. 30, 2014 CAD	Aug. 31, 2014 CAD property	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($) property shares	Dec. 31, 2013 USD ($) property	Jul. 31, 2014 CAD	Aug. 31, 2004 CAD
Business Acquisition [Line Items]
Amount paid for equity interest														$ 26,282	$ 0	$ 0
Ownership interests in properties accounted for under the equity method (as a percent)						5.00%								5.00%
Net real estate property						$ 19,625,220				$ 16,772,990				$ 19,625,220	16,772,990
Goodwill						1,047,497				363,971				1,047,497	363,971
Revenues						841,274	$ 827,606	$ 811,920	$ 805,598	732,090	$ 704,932	$ 674,529	$ 665,262	3,286,398	2,776,813	2,516,617
Business acquisition, transaction costs						99,000				10,800				99,000	10,800
Merger-related expenses and deal costs														102,944	43,304	21,634
Settlement of capital lease obligation														142,200
Unsecured Debt
Business Acquisition [Line Items]
Debt instrument, face amount						20,000								20,000
Unsecured Debt | Unsecured term loan due 2015
Business Acquisition [Line Items]
Business combination, repayment of debt | CAD				CAD 660.0
Debt instrument, face amount | CAD																	CAD 791.0
Triple-net leased properties
Business Acquisition [Line Items]
Net real estate property						9,300								9,300
Goodwill						312,315								$ 312,315
Triple-net leased properties | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties completed | property														1
Senior living operations
Business Acquisition [Line Items]
Goodwill						260,882								$ 260,882
MOB operations
Business Acquisition [Line Items]
Goodwill						474,300								474,300
2015 Acquisitions
Business Acquisition [Line Items]
Payments to acquire businesses														2,685,982
Business combination, notes payable and other debt assumed						177,857								177,857
Goodwill						746,900								746,900
Revenues														327,000
NOI														201,900
Business acquisition, transaction costs						4,100				1,400				4,100	1,400
2015 Acquisitions | Triple-net leased properties
Business Acquisition [Line Items]
Business combination, notes payable and other debt assumed						0								0
Goodwill						133,600								133,600
2015 Acquisitions | Senior living operations
Business Acquisition [Line Items]
Business combination, notes payable and other debt assumed						77,940								77,940
Goodwill						219,100								219,100
2015 Acquisitions | MOB operations
Business Acquisition [Line Items]
Business combination, notes payable and other debt assumed						99,917								99,917
Goodwill						394,200								394,200
American Realty Capital Healthcare Trust
Business Acquisition [Line Items]
Number of real estate properties acquired | property			152
Business combination, consideration transferred, stock conversion ratio, per acquiree share			0.1688
Business combination, consideration transferred, price per acquiree share (dollars per share) | $ / shares			$ 11.33
Payments to acquire businesses			$ 11,000
Business combination, notes payable and other debt assumed			167,000
Business combination, repayment of debt			$ 730,000
American Realty Capital Healthcare Trust | Common Stock
Business Acquisition [Line Items]
Business acquisition, equity interest issued, number of shares | shares			28,400,000
American Realty Capital Healthcare Trust | Skilled Nursing Facilities
Business Acquisition [Line Items]
Number of real estate properties acquired | property		20
Ardent
Business Acquisition [Line Items]
Estimated fair value of investment	$ 1,300,000
Amount paid for equity interest	$ 26,300
Ownership interests in properties accounted for under the equity method (as a percent)	9.90%
Ardent | Triple-net leased properties
Business Acquisition [Line Items]
Number of real estate properties acquired | property	10
Other 2015 Acquisitions
Business Acquisition [Line Items]
Business combination, consideration transferred														$ 612,000
Other 2015 Acquisitions | Skilled Nursing Facilities
Business Acquisition [Line Items]
Number of real estate properties acquired | property														12
Other 2015 Acquisitions | Triple-net leased properties
Business Acquisition [Line Items]
Number of real estate properties acquired | property														11
Other 2015 Acquisitions | MOB operations
Business Acquisition [Line Items]
Number of real estate properties acquired | property														11
Other 2015 Acquisitions | MOB operations | Unconsolidated Properties
Business Acquisition [Line Items]
Number of real estate properties acquired | property														8
Limited Partnership Units | Common Stock
Business Acquisition [Line Items]
Business acquisition, equity interest issued, number of shares | shares			1,100,000
2014 Acquisitions
Business Acquisition [Line Items]
Payments to acquire businesses														$ 1,469,217
Business combination, notes payable and other debt assumed						241,077								241,077
Revenues															75,900
NOI															41,500
Business acquisition, transaction costs										26,200					26,200
Merger-related expenses and deal costs															23,800
2014 Acquisitions | Triple-net leased properties
Business Acquisition [Line Items]
Payments to acquire businesses														599,782
Business combination, notes payable and other debt assumed						12,927								12,927
2014 Acquisitions | Senior living operations
Business Acquisition [Line Items]
Payments to acquire businesses														869,435
Business combination, notes payable and other debt assumed						228,150								228,150
Holiday Retirement
Business Acquisition [Line Items]
Business combination, notes payable and other debt assumed | CAD																		CAD 193.7
Business combination, consideration transferred | CAD					CAD 957.0
Early debt repayment costs | CAD					CAD 26.9
Holiday Retirement | Unsecured Debt | Unsecured term loan due 2015
Business Acquisition [Line Items]
Debt instrument, face amount | CAD																	CAD 791.0
Holiday Retirement | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired | property					29
Development Projects, 2014
Business Acquisition [Line Items]
Net real estate property										$ 41,200					$ 41,200
Development Projects, 2014 | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties completed | property															1
Development Projects, 2014 | Medical Office Buildings
Business Acquisition [Line Items]
Number of real estate properties completed | property															2
2013 Acquisitions
Business Acquisition [Line Items]
Payments to acquire businesses														1,581,487
Business combination, notes payable and other debt assumed						41,436								41,436
Business combination, consideration transferred																$ 1,800,000
2013 Acquisitions | Triple-net leased properties
Business Acquisition [Line Items]
Payments to acquire businesses														808,287
Business combination, notes payable and other debt assumed						36,300								36,300
2013 Acquisitions | Triple-net leased properties | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired | property																27
2013 Acquisitions | Senior living operations
Business Acquisition [Line Items]
Payments to acquire businesses														627,249
Business combination, notes payable and other debt assumed						5,136								$ 5,136
2013 Acquisitions | Senior living operations | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired | property																24
Number of real estate properties acquired, previously capital leases | property														8		8
2013 Acquisitions | MOB operations
Business Acquisition [Line Items]
Payments to acquire businesses														$ 145,951
Business combination, notes payable and other debt assumed						$ 0								$ 0
2013 Acquisitions | MOB operations | Medical Office Buildings
Business Acquisition [Line Items]
Number of real estate properties acquired | property																11
Development Projects, 2013
Business Acquisition [Line Items]
Net real estate property																$ 65,500
Development Projects, 2013 | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties completed | property																2
Development Projects, 2013 | Medical Office Buildings
Business Acquisition [Line Items]
Number of real estate properties completed | property																1
Development Projects, 2013 | Hospitals
Business Acquisition [Line Items]
Number of real estate properties completed | property																1
Other Acquisitions
Business Acquisition [Line Items]
Business combination, consideration transferred															$ 812,000
Early debt repayment costs															$ 18,800
Other Acquisitions | Triple-net leased properties | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired | property															26
Other Acquisitions | Triple-net leased properties | Private Hospitals
Business Acquisition [Line Items]
Number of real estate properties acquired | property															3
Other Acquisitions | Senior living operations | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired | property															4
Other Acquisitions | MOB operations
Business Acquisition [Line Items]
Business acquisition, equity interest issued, number of shares | shares															148,241