Acquisitions - Additional Information (Detail) $ in Millions							3 Months Ended	12 Months Ended
	Jan. 31, 2017 USD ($) Community	Nov. 02, 2016 USD ($) Community Independent_Living_Unit Assisted_Living_Unit	Sep. 30, 2016 USD ($) Community Independent_Living_Unit Assisted_Living_Unit	Sep. 27, 2016 USD ($) Community Assisted_Living_Unit	Feb. 16, 2016 USD ($) Community Assisted_Living_Unit	Jan. 26, 2016 USD ($) Community Assisted_Living_Unit	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Additions to property and equipment								$ 126.0
Valuation adjustments									$ 1.3
Revenue generated from acquisition									15.5
Losses before income taxes due to acquisition									$ (7.7)
Other Asset [Member]
Business Acquisition [Line Items]
Finite lived intangible asset acquired in place leases during period								$ 12.8
Ventas [Member]
Business Acquisition [Line Items]
Acquisition cost	$ 85.0
Number of acquisition closed | Community	4
Payments for rent	$ 2.3
Number of remaining lease communities | Community	7
Lease termination obligation	$ 16.0
Estimated fair value of the acquired entities	88.1
Business acquisition, aggregate consideration	101.0
Loss on facility lease termination							$ 12.9
Transaction cost related to acquisition	$ 0.4
Additions to property and equipment							88.1
Reclassification of property and equipment to other assets							$ 1.3
Ventas [Member] | Minimum [Member]
Business Acquisition [Line Items]
Long term fixed interest rate	7.25%
Ventas [Member] | Maximum [Member]
Business Acquisition [Line Items]
Long term fixed interest rate	8.50%
Cincinnati, Ohio [Member]
Business Acquisition [Line Items]
Acquisition cost		$ 29.0
Number of acquisition closed | Community		1
Long term fixed interest rate		4.24%
Transaction cost related to acquisition		$ 0.2
Number of independent living units | Independent_Living_Unit		45
Number of assisted living units | Assisted_Living_Unit		77
Long term finance		$ 22.0
Maximum period for expansion of permanent financing		10 years
Springfield Massachusetts [Member]
Business Acquisition [Line Items]
Acquisition cost			$ 27.0
Number of acquisition closed | Community			1
Long term fixed interest rate			4.10%
Transaction cost related to acquisition			$ 0.3
Number of independent living units | Independent_Living_Unit			97
Number of assisted living units | Assisted_Living_Unit			90
Long term finance			$ 20.3
Maximum period for expansion of permanent financing			10 years
Kingwood Texas [Member]
Business Acquisition [Line Items]
Acquisition cost				$ 18.0
Number of acquisition closed | Community				1
Long term fixed interest rate				4.13%
Transaction cost related to acquisition				$ 0.2
Number of assisted living units | Assisted_Living_Unit				96
Long term finance				$ 13.0
Maximum period for expansion of permanent financing				15 years
Pensacola Florida [Member]
Business Acquisition [Line Items]
Acquisition cost					$ 48.0
Number of acquisition closed | Community					2
Long term fixed interest rate					4.38%
Transaction cost related to acquisition					$ 0.3
Number of assisted living units | Assisted_Living_Unit					179
Long term finance					$ 35.0
Maximum period for expansion of permanent financing					10 years
Colby Park Falls [Member]
Business Acquisition [Line Items]
Acquisition cost						$ 16.8
Number of acquisition closed | Community						3
Long term fixed interest rate						4.50%
Transaction cost related to acquisition						$ 0.1
Number of assisted living units | Assisted_Living_Unit						138
Long term finance						$ 11.3
Maximum period for expansion of permanent financing						10 years
Bridge Loan [Member] | Ventas [Member]
Business Acquisition [Line Items]
Acquisition cost	$ 65.0
Initial variable interest rate	4.00%
Bridge loan period	36 months