Debt Obligations (Details)	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Debt Obligations
Applicable Interest Rate			4.07%
Outstanding Balance		$ 571,872,000	$ 571,872,000	$ 280,584,000
Proceeds from issuance of senior unsecured notes			200,000,000	30,000,000	$ 70,000,000
Amount outstanding Senior Unsecured Notes		451,372,000	451,372,000	280,584,000
Scheduled Principal Payments
Total		572,967,000	572,967,000
2016		26,667,000	26,667,000
2017		31,167,000	31,167,000
2018		154,667,000	154,667,000
2019		32,666,000	32,666,000
2020		37,160,000	37,160,000
Thereafter		290,640,000	$ 290,640,000
Bank Borrowings - Line of Credit
Debt Obligations
Applicable Interest Rate			1.92%
Outstanding Balance		120,500,000	$ 120,500,000
Available for Borrowing		479,500,000	479,500,000	400,000,000
Amount borrowed			291,000,000	37,500,000
Maximum availability under Unsecured Credit Agreement		600,000,000	$ 600,000,000
Increase in bank borrowings		$ 200,000,000
Extension of maturity date			1 year
Description of interest rate			LIBOR
Basis spread over base rate (as a percent)			1.50%
Unused commitment fee (as a percent)			0.35%
Maximum ratio of total indebtedness to total asset value		0.5	0.5
Maximum ratio of secured debt to total asset value		0.35	0.35
Maximum ratio of unsecured debt to the value of the unencumbered asset pool		0.6	0.6
Minimum ratio of EBITDA to fixed charges		1.50	1.50
Repayment amount			$ 170,500,000	58,500,000
Scheduled Principal Payments
Total		$ 120,500,000	120,500,000
2018		120,500,000	$ 120,500,000
Bank Borrowings - Line of Credit | Subsequent Event
Debt Obligations
Available for Borrowing	$ 447,500,000
Amount borrowed	32,000,000
Senior Unsecured Debt
Debt Obligations
Applicable Interest Rate			4.64%
Outstanding Balance		451,372,000	$ 451,372,000	280,584,000
Available for Borrowing		33,333,000	33,333,000
Repayments of debt			29,167,000	4,167,000
Scheduled Principal Payments
Total		452,467,000	452,467,000
2016		26,667,000	26,667,000
2017		31,167,000	31,167,000
2018		34,167,000	34,167,000
2019		32,666,000	32,666,000
2020		37,160,000	37,160,000
Thereafter		290,640,000	290,640,000
Debt issuance costs			$ 1,095,000
Senior Unsecured Debt | Maximum
Debt Obligations
Maturity Period			15 years
Senior Unsecured Debt | Weighted Average
Debt Obligations
Maturity Period			12 years
Private Shelf Agreement Prudential
Debt Obligations
Maximum availability under Unsecured Credit Agreement		200,000,000	$ 200,000,000
Maturity Period			3 years
Senior Unsecured Term Notes 3.99 Percent Due 20 November 2021 [Member]
Debt Obligations
Proceeds from issuance of senior unsecured notes				$ 30,000,000
Stated interest rate (as a percent)				4.50%
Senior Unsecured Term Note 4.50 Percent Due 31 July 2026 [Member]
Debt Obligations
Available for Borrowing		$ 37,500,000	$ 37,500,000
Proceeds from issuance of senior unsecured notes			$ 100,000,000
Stated interest rate (as a percent)		4.50%	4.50%
Note Purchase and Private Shelf Agreement AIG
Debt Obligations
Maximum available for issuance under private shelf agreement			$ 100,000,000
Bonds
Debt Obligations
Face amount of debt		$ 1,400,000	1,400,000
Repayments of debt			$ 635,000
Number of assisted living properties securing debt instruments | property			5
Senior Unsecured Debt
Debt Obligations
Available for Borrowing		$ 479,500,000	$ 479,500,000
Senior Unsecured Debt | Subsequent Event
Debt Obligations
Outstanding Balance	152,500,000
Available for Borrowing	447,500,000
Amount borrowed	$ 32,000,000
Senior Unsecured Debt | Note Purchase and Private Shelf Agreement AIG
Debt Obligations
Stated interest rate (as a percent)		4.26%	4.26%
Maturity Period			3 years