Description of Business and Significant Accounting Policies - Property and Equipment and Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 5.0	$ 4.8	$ 4.4
Housekeeping and Dietary equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Housekeeping and Dietary equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	7 years
Computer hardware and software | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Computer hardware and software | Maximum
Property, Plant and Equipment [Line Items]
Useful life	7 years
Autos and Trucks | Minimum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Autos and Trucks | Maximum
Property, Plant and Equipment [Line Items]
Useful life	10 years