Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2018	Dec. 31, 2018 USD ($) Group visit PeriodicRate shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)	Nov. 30, 2018 USD ($)	Apr. 01, 2018 shares
Summary Of Significant Accounting Policies [Line Items]
Percentage equity ownership, license leasing agreements										100.00%
Net service revenue	$ (509,842,000)	$ (507,043,000)	$ (502,024,000)	$ (291,054,000)	$ (291,140,000)	$ (269,678,000)	$ (257,535,000)	$ (244,249,000)		$ (1,809,963,000)	$ (1,062,602,000)	$ (900,033,000)
Selected number of Medicare home health groups | Group										1
Number of Medicare home health resource groups | Group										153
Number of days from date RAP paid to submit final Medicare bill										60 days
Medicare sequestration reduction for episodes									2.00%
Low utilization adjustment visits | visit										5
Selected hospice, periodic rates used to calculate revenue | PeriodicRate										1
Number of hospice, periodic rates used to calculate revenue | PeriodicRate										4
Minimum percentage of Medicare reimbursement from inpatient care services that subjects individual programs to inpatient cap										20.00%
Determination period for hospice Medicare inpatient reimbursement cap										12 months
Medicare credit risk for accounts receivable	55.00%									55.00%
Reimbursement for initial episode of care										60.00%
Number of days from start of episode to submit final Medicare bill										120 days
Reimbursement for subsequent episodes of care										50.00%
Workers' compensation, maximum coverage per incident										$ 500,000
Stop-loss insurance purchased										300,000
Goodwill impairment loss										0	0	0
Disposal related to goodwill associated with closure of underperforming locations	$ 600,000				$ 1,500,000					600,000	1,500,000
Amortization expense										2,100,000	2,100,000	2,500,000
Disposal related to intangible assets	$ 3,700,000									3,700,000				$ 3,700,000
Loss on impairment of intangible assets										0	0
Impairment of long-lived assets										0	0	0
Depreciation expense										$ 14,100,000	$ 11,300,000	9,700,000
Common stock, shares authorized | shares	60,000,000				40,000,000					60,000,000	40,000,000				60,000,000.0
Minimum
Summary Of Significant Accounting Policies [Line Items]
Intangible asset estimated useful life										2 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Intangible asset estimated useful life										10 years
Buildings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives										39 years
Transportation Equipment, Furniture and Other Equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives										3 years
Transportation Equipment, Furniture and Other Equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives										10 years
ASU 2014-09 | Adjustment for ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Net service revenue										$ 25,500,000	$ 9,484,000	14,790,000
Healthcare innovations
Summary Of Significant Accounting Policies [Line Items]
Net service revenue										(33,103,000)	$ 0	$ 0
Accountable Care Organizations | Healthcare innovations
Summary Of Significant Accounting Policies [Line Items]
Net service revenue related to the 2017 ACO service periods										3,700,000
Subsequent Event | Scenario, Forecast | ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Increase in total assets													$ 90,000,000
Increase in total liabilities													$ 90,000,000
General liability
Summary Of Significant Accounting Policies [Line Items]
Maximum coverage per incident										100,000
D&O coverage | Minimum
Summary Of Significant Accounting Policies [Line Items]
Deductibles										500,000
D&O coverage | Maximum
Summary Of Significant Accounting Policies [Line Items]
Deductibles										$ 1,000,000