Summary of Significant Accounting Policies - Percentage of Net Service Revenue Earned by Category of Payor (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%
Home health
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%
Home health | Medicare
Significant Accounting Policies [Line Items]
Percentage of net service revenue	71.80%	72.60%	76.80%
Home health | Medicaid
Significant Accounting Policies [Line Items]
Percentage of net service revenue	1.30%	1.10%	1.00%
Home health | Managed Care, Commercial, and Other
Significant Accounting Policies [Line Items]
Percentage of net service revenue	26.90%	26.30%	22.20%
Hospice
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%
Hospice | Medicare
Significant Accounting Policies [Line Items]
Percentage of net service revenue	90.70%	92.90%	94.80%
Hospice | Medicaid
Significant Accounting Policies [Line Items]
Percentage of net service revenue	0.40%	0.30%	0.90%
Hospice | Managed Care, Commercial, and Other
Significant Accounting Policies [Line Items]
Percentage of net service revenue	8.90%	6.80%	4.30%
Home and Community-Based
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%
Home and Community-Based | Medicaid
Significant Accounting Policies [Line Items]
Percentage of net service revenue	23.90%	18.90%	15.20%
Home and Community-Based | Managed Care, Commercial, and Other
Significant Accounting Policies [Line Items]
Percentage of net service revenue	76.10%	81.10%	84.80%
Facility-based
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	100.00%	100.00%
Facility-based | Medicare
Significant Accounting Policies [Line Items]
Percentage of net service revenue	59.70%	63.70%	72.50%
Facility-based | Managed Care, Commercial, and Other
Significant Accounting Policies [Line Items]
Percentage of net service revenue	40.30%	36.30%	27.50%
Healthcare innovations
Significant Accounting Policies [Line Items]
Percentage of net service revenue	100.00%	0.00%	0.00%
Healthcare innovations | Medicare
Significant Accounting Policies [Line Items]
Percentage of net service revenue	22.80%	0.00%	0.00%
Healthcare innovations | Medicaid
Significant Accounting Policies [Line Items]
Percentage of net service revenue	0.30%	0.00%	0.00%
Healthcare innovations | Managed Care, Commercial, and Other
Significant Accounting Policies [Line Items]
Percentage of net service revenue	76.90%	0.00%	0.00%