Significant Accounting Policies - Percentage of Net Service Revenue Earned by Category of Payor (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%	100.00%
Home health services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%	100.00%
Hospice services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%	100.00%
Home and community-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%	100.00%
Facility-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%	100.00%
HCI
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	100.00%	0.00%	100.00%	0.00%
Medicare | Home health services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	72.00%	72.50%	72.20%	72.80%
Medicare | Hospice services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	88.40%	92.10%	90.50%	93.00%
Medicare | Facility-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	56.70%	63.20%	59.90%	64.00%
Medicare | HCI
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	16.80%	0.00%	21.10%	0.00%
Medicaid | Home health services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	1.20%	1.10%	1.30%	1.20%
Medicaid | Hospice services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	1.00%	0.00%	0.70%	0.40%
Medicaid | Home and community-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	23.80%	22.30%	23.40%	19.10%
Medicaid | HCI
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	0.20%	0.00%	0.30%	0.00%
Managed Care, Commercial, and Other | Home health services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	26.80%	26.40%	26.50%	26.00%
Managed Care, Commercial, and Other | Hospice services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	10.60%	7.90%	8.80%	6.60%
Managed Care, Commercial, and Other | Home and community-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	76.20%	77.70%	76.60%	80.90%
Managed Care, Commercial, and Other | Facility-based services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	43.30%	36.80%	40.10%	36.00%
Managed Care, Commercial, and Other | HCI
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of net service revenue	83.00%	0.00%	78.60%	0.00%