Segment Reporting Segment Reporting - Table 5 (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues	$ 879.3	$ 778.6	$ 764.4	$ 740.6	$ 613.4	$ 596.9	$ 604.4	$ 591.2	$ 3,162.9	$ 2,405.9	$ 2,273.2
Inpatient Rehabilitation Hospital [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									2,653.1	2,377.3	2,244.4
Inpatient [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									2,547.2	2,272.5	2,130.8
Outpatient and other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									105.9	104.8	113.6
Home Health and Hospice [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									509.8	28.6	28.8
Home health [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									478.1	28.6	28.8
Hospice [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net operating revenues									$ 31.7	$ 0.0	$ 0.0