Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Contingency [Line Items]
Effective income tax rate	53.20%	42.20%
Effective income tax rate increase (decrease) during period	3.00%
Concentra Inc.
Income Tax Contingency [Line Items]
Effective income tax rate increase (decrease) during period		(7.00%)
Deferred tax asset		$ 53