Segment Reporting Segment Reporting - Table 1 (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 Information [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
Less: Provision for doubtful accounts									(47.2)	(31.6)	(26.0)
Net operating revenues less provision for doubtful accounts									3,115.7	2,374.3	2,247.2
Costs and Expenses [Abstract]
Salaries and benefits									1,670.8	1,161.7	1,089.7
Other operating expenses									432.1	351.6	323.0
Supplies									128.7	111.9	105.4
Occupancy costs									53.9	41.6	47.0
Total segment level operating expenses									2,569.0	1,906.9	1,764.9
Other income									(5.5)	(31.2)	(4.5)
Equity in net income of nonconsolidated affiliates									(8.7)	(10.7)	(11.2)
Noncontrolling interest	$ (18.8)	$ (17.1)	$ (17.3)	$ (16.5)	$ (15.4)	$ (14.7)	$ (14.8)	$ (14.8)	(69.7)	(59.7)	(57.8)
Inpatient Rehabilitation Hospital [Member]
Segment Reporting Information [Line Items]
Net operating revenues									2,653.1	2,377.3	2,244.4
Less: Provision for doubtful accounts									44.7	31.2	25.6
Net operating revenues less provision for doubtful accounts									2,608.4	2,346.1	2,218.8
Costs and Expenses [Abstract]
Salaries and benefits									1,310.6	1,141.0	1,069.7
Other operating expenses									387.7	342.5	314.7
Supplies									120.9	111.5	105.2
Occupancy costs									46.2	41.2	46.5
Cost of services sold (excluding depreciation and amortization)									0.0	0.0	0.0
Support and overhead costs									0.0	0.0	0.0
Total segment level operating expenses									1,865.4	1,636.2	1,536.1
Other income									2.3	4.0	4.5
Equity in net income of nonconsolidated affiliates									8.6	10.7	11.2
Noncontrolling interest									(62.9)	(59.3)	(57.2)
Segment Adjusted EBITDA									691.0	665.3	641.2
Capital Expenditures									151.7	187.9	216.5
Home Health and Hospice [Member]
Segment Reporting Information [Line Items]
Net operating revenues									509.8	28.6	28.8
Less: Provision for doubtful accounts									2.5	0.4	0.4
Net operating revenues less provision for doubtful accounts									507.3	28.2	28.4
Costs and Expenses [Abstract]
Salaries and benefits									0.0	0.0	0.0
Other operating expenses									0.0	0.0	0.0
Supplies									0.0	0.0	0.0
Occupancy costs									0.0	0.0	0.0
Cost of services sold (excluding depreciation and amortization)									244.8	17.0	16.7
Support and overhead costs									172.7	6.9	6.6
Total segment level operating expenses									417.5	23.9	23.3
Other income									0.0	0.0	0.0
Equity in net income of nonconsolidated affiliates									0.1	0.0	0.0
Noncontrolling interest									(6.8)	(0.4)	(0.6)
Segment Adjusted EBITDA									83.1	3.9	4.5
Capital Expenditures									$ 5.8	$ 0.0	$ 0.0