Real Estate Properties - Acquisitions (Details)		1 Months Ended																										3 Months Ended	5 Months Ended	12 Months Ended
	Jun. 29, 2016 pooling_agreement	Jan. 31, 2017 ft² living_unit	Jan. 31, 2017 ft² building	Jan. 31, 2017 ft² community	Dec. 31, 2016 USD ($) ft² state living_unit community lease_agreement property	Oct. 31, 2016 USD ($) ft² building property	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($) state living_unit community lease_agreement property pooling_agreement	May 31, 2016 USD ($) ft² living_unit building community property	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($) ft² building property	Dec. 31, 2015 USD ($) ft² living_unit	Sep. 30, 2015 USD ($) living_unit community property	Aug. 31, 2015 USD ($)	Jul. 31, 2015 USD ($)	May 31, 2015 USD ($) living_unit community property	Feb. 28, 2015 USD ($)	Jan. 31, 2015 USD ($) ft² living_unit building property	Dec. 31, 2014 USD ($) ft² living_unit	Dec. 31, 2014 USD ($) ft² living_unit community	Dec. 31, 2014 USD ($) ft² living_unit lease_agreement	Dec. 31, 2014 USD ($) ft² living_unit property	Oct. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	May 31, 2014 USD ($) ft² property	Apr. 30, 2014 USD ($) ft² property	Jan. 31, 2014 USD ($)	Mar. 31, 2016 operator community	Sep. 30, 2015 USD ($) living_unit community company	Dec. 31, 2016 USD ($) ft² state living_unit community property	Dec. 31, 2015 USD ($) ft² living_unit community property	Dec. 31, 2014 USD ($) ft² living_unit building community property	Feb. 28, 2016 USD ($) management_agreement
Real Estate Properties
Number of states in which properties are located | state					42																									42
Payment for land parcel adjacent to a senior living community leased to Five Star																	$ 490,000
Acquired Real Estate Leases					$ 775,935,000							$ 779,761,000																		$ 775,935,000	$ 779,761,000
Intangible lease liabilities recorded					(137,351,000)							(139,346,000)																		(137,351,000)	(139,346,000)
Assumed Debt																														0	(181,433,000)	$ (15,630,000)
Above market lease
Real Estate Properties
Acquired Real Estate Leases					43,906,000							48,048,000																		43,906,000	48,048,000
Original value lease
Real Estate Properties
Acquired Real Estate Leases					$ 732,029,000							731,713,000																		732,029,000	731,713,000
Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable																	39,000													$ 1,719,000	$ 1,734,000	$ 2,066,000
Number of pre-existing management agreements terminated | pooling_agreement								3
Number of pre-existing management agreements | lease_agreement					1			4
Number of communities associated with leases in default | community					5
Lease termination fee					$ 115,000
Five Star | TRS
Real Estate Properties
Proceeds from settlement agreement										$ 2,365,000
Senior Living Communities
Real Estate Properties
Number of Properties | property																															39	2
Number of communities | community																													19
Senior Living Communities | Five Star
Real Estate Properties
Number of properties acquired, referred to as managed properties | living_unit																														68
Increase or decrease in annual lease rent payable												$ (2,000)
Number of pre-existing management agreements terminated | pooling_agreement	3
Number of pre-existing management agreements | pooling_agreement	4
Number of separate management agreements entered for communities acquired | pooling_agreement	10							10
MOBs
Real Estate Properties
Number of Properties | living_unit																		23
Acquisition
Real Estate Properties
Number of Properties | living_unit																		23
Weighted average interest rate on debt (as a percent)																		4.73%
Acquisition | Senior Living Communities
Real Estate Properties
Purchase price excluding closing costs													$ 18,250,000			$ 9,750,000
Cash paid plus assumed debt																															$ 818,236,000	$ 47,430,000
Number of communities | community													1
Number of living units | living_unit												3,563	84						228	228	228	228							84		3,563	228
Weighted average interest rate on debt (as a percent)																															4.57%
Fees paid to terminate the agreement													$ 975,000																$ 975,000
Purchase price amount withheld until seller satisfies various conditions																$ 1,000,000
Acquired Real Estate Leases												$ 130,305,000							$ 3,119,000	$ 3,119,000	$ 3,119,000	$ 3,119,000									$ 130,305,000	$ 3,119,000
Other Liabilities												$ (18,091,000)							0	0	0	0									(18,091,000)	0
Assumed Debt																															(151,477,000)	0
(Premium) / Discount on Assumed Debt																															$ (858,000)	$ 0
Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Other Liabilities																																	$ (1,000,000)
Number of management agreements | management_agreement																																	1
Acquisition | Senior Living Communities | Five Star
Real Estate Properties
Number of private pay independent living units | living_unit																40
Number of communities | community																1
Acquisition | Triple Net Leased Senior Living Communities
Real Estate Properties
Number of communities | community																													19
Number of living units | living_unit													2,206																2,206
Number of operators | company																													7
Weighted average amortization period																													11 years 6 months
Acquisition | Managed Senior Living Communities
Real Estate Properties
Number of communities | community																													5
Number of living units | living_unit													395																395
Number of pre-existing management agreements terminated | community																													14
Acquisition | Managed Senior Living Communities | TRS
Real Estate Properties
Number of communities | community																													19
Number of living units | living_unit													1,233																1,233
Acquisition | Managed Senior Living Communities | Five Star
Real Estate Properties
Number of living units | living_unit													838																838
Number of separate management agreements entered for communities acquired | community																													14
Acquisition | Managed Senior Living Communities | Five Star | TRS
Real Estate Properties
Number of Properties | community									1
Number of private pay independent living units | living_unit									38
Acquisition | Senior Living Community Subtotal
Real Estate Properties
Number of Properties | property																														10	38
Cash paid plus assumed debt																														$ 139,493,000	$ 790,077,000
Number of living units | living_unit					709							3,439																		709	3,439
Acquired Real Estate Leases					$ 3,723,000							$ 130,144,000																		$ 3,723,000	$ 130,144,000
Other Liabilities					0							(18,091,000)																		0	(18,091,000)
Assumed Debt																														0	(151,477,000)
(Premium) / Discount on Assumed Debt																														$ 0	$ (858,000)
Acquisition | MOBs
Real Estate Properties
Number of Properties | property																														3	23	2
Purchase price excluding closing costs																		$ 539,000,000
Cash paid plus assumed debt																														$ 86,432,000	$ 531,623,000	$ 1,162,584,000
Net closing adjustments																		7,377,000
Acquired Real Estate Leases					9,645,000							87,780,000							410,954,000	410,954,000	410,954,000	410,954,000								9,645,000	87,780,000	410,954,000
Intangible lease liabilities recorded					$ (1,091,000)							$ (3,150,000)							$ (118,429,000)	$ (118,429,000)	$ (118,429,000)	$ (118,429,000)								(1,091,000)	(3,150,000)	(118,429,000)
Assumed Debt																		$ (29,955,000)														(15,630,000)
(Premium) / Discount on Assumed Debt																														$ 0	$ (1,073,000)	$ (1,013,000)
Number of buildings acquired | building																		23														3
Area of real estate properties (in square feet) | ft²					390,000							2,170,000							1,776,277	1,776,277	1,776,277	1,776,277								390,000	2,170,000	1,776,277
Acquisition | MOBs | Weighted Average
Real Estate Properties
Below market, acquired lease amortization period																		11 years 2 months 12 days
Acquisition | MOBs | Above market lease | Weighted Average
Real Estate Properties
Acquired lease amortization period																		9 years 6 months
Acquisition | MOBs | Original value lease | Weighted Average
Real Estate Properties
Acquired lease amortization period																		9 years 8 months 12 days
Agreement to Acquire | Senior Living Communities
Real Estate Properties
Number of Properties | community													1			37
Purchase price excluding closing costs																			$ 790,000,000
Number of communities																				38	38											38
Number of living units | living_unit																			3,439	3,439	3,439	3,439										3,439
Net closing adjustments																			$ 77,000
Weighted average interest rate on debt (as a percent)																4.57%
Assumed Debt																$ (151,477,000)
Land | Acquisition | Senior Living Communities
Real Estate Properties
Property plant and equipment acquired																															$ 47,589,000	$ 2,803,000
Land | Acquisition | Senior Living Community Subtotal
Real Estate Properties
Property plant and equipment acquired																														$ 13,226,000	43,117,000
Land | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																														7,845,000	50,429,000	55,784,000
Building improvements | Acquisition | Senior Living Communities
Real Estate Properties
Property plant and equipment acquired																															623,474,000	40,819,000
Building improvements | Acquisition | Senior Living Community Subtotal
Real Estate Properties
Property plant and equipment acquired																														114,512,000	601,284,000
Building improvements | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																														70,033,000	397,637,000	815,288,000
Furniture, fixtures and equipment | Acquisition | Senior Living Communities
Real Estate Properties
Property plant and equipment acquired																															35,817,000	689,000
Furniture, fixtures and equipment | Acquisition | Senior Living Community Subtotal
Real Estate Properties
Property plant and equipment acquired																														$ 8,033,000	$ 34,481,000
11 States | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Number of Properties | property																18
Cash paid plus assumed debt																$ 459,184,000
Number of living units | living_unit																2,119
Acquired Real Estate Leases																$ 54,096,000
Other Liabilities																(18,091,000)
Assumed Debt																(44,395,000)
(Premium) / Discount on Assumed Debt																(1,125,000)
11 States | Land | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired																29,716,000
11 States | Building improvements | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired																373,471,000
11 States | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired																$ 21,117,000
5 States | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Number of Properties | property																19
Cash paid plus assumed debt																$ 313,345,000
Number of living units | living_unit																1,233
Acquired Real Estate Leases																$ 73,840,000
Other Liabilities																0
Assumed Debt																(94,785,000)
(Premium) / Discount on Assumed Debt																832,000
5 States | Land | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																12,267,000
5 States | Building improvements | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																214,064,000
5 States | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																$ 12,342,000
North Carolina | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Number of Properties | property													1
Cash paid plus assumed debt													$ 17,548,000
Number of living units | living_unit													87																87
Acquired Real Estate Leases													$ 2,208,000																$ 2,208,000
Other Liabilities													0																$ 0
Assumed Debt													(12,297,000)
(Premium) / Discount on Assumed Debt													(565,000)
North Carolina | Land | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													1,134,000
North Carolina | Building improvements | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													13,749,000
North Carolina | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													$ 1,022,000
Georgia | Senior Living Communities | Five Star
Real Estate Properties
Number of communities associated with leases in default | community																														5
Georgia | Land Parcel | Five Star
Real Estate Properties
Cash paid plus assumed debt					$ 1,600,000
Georgia | Managed Senior Living Communities | Five Star | TRS
Real Estate Properties
Purchase price excluding closing costs									$ 8,400,000
Georgia | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Number of Properties | property													1
Cash paid plus assumed debt													$ 18,409,000
Number of living units | living_unit													84																84
Acquired Real Estate Leases													$ 0																$ 0
Other Liabilities													0																$ 0
Assumed Debt													0
(Premium) / Discount on Assumed Debt													0
Georgia | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Number of Properties | property									1							0
Cash paid plus assumed debt									$ 8,400,000							$ 9,750,000
Number of living units | living_unit									38							40
Acquired Real Estate Leases									$ 1,400,000							$ 161,000
Other Liabilities									0							0
Assumed Debt									0							0
(Premium) / Discount on Assumed Debt									0							0
Georgia | Land | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													3,479,000
Georgia | Land | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired									327,000							993,000
Georgia | Building improvements | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													14,021,000
Georgia | Building improvements | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired									6,195,000							8,169,000
Georgia | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired													$ 909,000
Georgia | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired									$ 478,000							$ 427,000
Four States | Senior Living Communities
Real Estate Properties
Number of Properties | community								7
Number of private pay independent living units | living_unit								545
Number of states in which properties are located | state								4
Cash paid plus assumed debt								$ 112,350,000
Operating leases annual rent																																$ 8,426,000
Four States | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Number of Properties | property								7
Cash paid plus assumed debt								$ 112,493,000
Number of living units | living_unit								545
Acquired Real Estate Leases								$ 0
Other Liabilities								0
Assumed Debt								0
(Premium) / Discount on Assumed Debt								0
Four States | Land | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired								11,085,000
Four States | Building improvements | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired								94,940,000
Four States | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired								$ 6,468,000
Florida | Senior Living Communities | Five Star
Real Estate Properties
Purchase price excluding closing costs							$ 130,000
Florida | MOBs
Real Estate Properties
Number of Properties | property									1
Cash paid plus assumed debt									$ 45,000,000
Number of buildings acquired | building									1
Area of real estate properties (in square feet) | ft²									166,000
Ohio | MOBs
Real Estate Properties
Number of Properties | property						1
Purchase price excluding closing costs						$ 18,500,000
Number of buildings acquired | building						1
Area of real estate properties (in square feet) | ft²						96,000
Acquired lease amortization period						14 years 1 month 6 days
Below market, acquired lease amortization period						14 years 1 month 6 days
Illinois | Senior Living Communities | Five Star
Real Estate Properties
Number of Properties | community					2
Number of private pay independent living units | living_unit					126
Cash paid plus assumed debt					$ 18,600,000
Increase or decrease in annual lease rent payable					$ 1,395,000		10,000
Illinois | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Number of Properties | property					2
Cash paid plus assumed debt					$ 18,600,000
Number of living units | living_unit					126																									126
Acquired Real Estate Leases					$ 2,323,000																									$ 2,323,000
Other Liabilities					0																									0
Assumed Debt					0
(Premium) / Discount on Assumed Debt					0
Illinois | Land | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired					1,814,000
Illinois | Building improvements | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired					13,377,000
Illinois | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Leasing Member
Real Estate Properties
Property plant and equipment acquired					$ 1,087,000
Wisconsin One | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Number of Properties | property																						1
Cash paid plus assumed debt																			$ 7,000,000
Number of living units | living_unit																			52	52	52	52										52
Acquired Real Estate Leases																			$ 849,000	$ 849,000	$ 849,000	$ 849,000										$ 849,000
Other Liabilities																			0	$ 0	$ 0	$ 0										$ 0
Assumed Debt																			0
(Premium) / Discount on Assumed Debt																			0
Wisconsin One | Land | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			188,000
Wisconsin One | Building improvements | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			5,862,000
Wisconsin One | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			101,000
Wisconsin Two | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Number of Properties | property																						1
Cash paid plus assumed debt																			$ 40,430,000
Number of living units | living_unit																			176	176	176	176										176
Acquired Real Estate Leases																			$ 2,270,000	$ 2,270,000	$ 2,270,000	$ 2,270,000										$ 2,270,000
Other Liabilities																			0	$ 0	$ 0	$ 0										0
Assumed Debt																			0
(Premium) / Discount on Assumed Debt																			0
Wisconsin Two | Land | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			2,615,000
Wisconsin Two | Building improvements | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			34,957,000
Wisconsin Two | Furniture, fixtures and equipment | Acquisition | Senior Living Communities | Non Leasing Member
Real Estate Properties
Property plant and equipment acquired																			$ 588,000
12 States | Acquisition | MOBs
Real Estate Properties
Number of Properties | property						1			1		1							23
Cash paid plus assumed debt						$ 18,500,000			$ 45,232,000		$ 22,700,000							$ 531,623,000
Acquired Real Estate Leases						4,592,000			0		5,053,000							87,780,000
Intangible lease liabilities recorded						0			0		(1,091,000)							(3,150,000)
Assumed Debt						0			0		0							(29,955,000)												$ 0		$ (15,630,000)
(Premium) / Discount on Assumed Debt						$ 0			$ 0		$ 0							$ (1,073,000)
Area of real estate properties (in square feet) | ft²						96,000			166,000		128,000							2,170,000
12 States | Land | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired						$ 1,025,000			$ 2,792,000		$ 4,028,000							$ 50,429,000
12 States | Building improvements | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired						$ 12,883,000			$ 42,440,000		$ 14,710,000							$ 397,637,000
Pennsylvania | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable																	$ 23,000
Texas | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable																											$ 210,000
Texas | Acquisition | MOBs
Real Estate Properties
Number of Properties | property																										1
Cash paid plus assumed debt																										$ 32,932,000
Acquired Real Estate Leases																										7,672,000
Intangible lease liabilities recorded																										(10,000)
Assumed Debt																										(15,630,000)
(Premium) / Discount on Assumed Debt																										$ (1,013,000)
Area of real estate properties (in square feet) | ft²																										125,000
Texas | Land | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																										$ 3,141,000
Texas | Building improvements | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																										$ 23,142,000
Massachusetts | Acquisition | MOBs
Real Estate Properties
Number of Properties | property																									1
Cash paid plus assumed debt																									$ 1,129,652,000
Acquired Real Estate Leases																									403,282,000
Intangible lease liabilities recorded																									(118,419,000)
Assumed Debt																									0
(Premium) / Discount on Assumed Debt																									$ 0
Area of real estate properties (in square feet) | ft²																									1,651,000
Massachusetts | Land | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																									$ 52,643,000
Massachusetts | Building improvements | Acquisition | MOBs
Real Estate Properties
Property plant and equipment acquired																									$ 792,146,000
Iowa | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable															$ (16,000)
Wisconsin | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable														$ (85,000)										$ 452,000
Minnesota | MOBs
Real Estate Properties
Number of Properties | property											1
Purchase price excluding closing costs											$ 22,700,000
Number of buildings acquired | building											3
Area of real estate properties (in square feet) | ft²											128,000
Acquired lease amortization period											6 years 4 months 24 days
Below market, acquired lease amortization period											7 years 3 months 18 days
Virginia | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable																							$ (285,000)
Arizona | Senior Living Communities | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable																							$ (590,000)
Discontinued operations, disposed of by sale | Five Star
Real Estate Properties
Increase or decrease in annual lease rent payable							$ 25,000
Discontinued operations, held for sale | Senior Living Communities
Real Estate Properties
Number of living units | living_unit												140																			140
Discontinued operations, held for sale | Triple Net Leased Senior Living Communities
Real Estate Properties
Number of communities | community																												2			3
Number of tenants | operator																												2
Subsequent Event | Kansas
Real Estate Properties
Number of Properties		1		15,500
Number of buildings acquired | building			1
Area of real estate properties (in square feet) | ft²		117,000	117,000	117,000