Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) D Number_of_Visits	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Episode of care as episodic-based revenue, days | D					60
Percentage of total reimbursement of outlier payment					10.00%
Low utilization payment adjustment, maximum number of visits | Number_of_Visits					5
First threshold of therapy services required, visits | Number_of_Visits					6
Second threshold of services required, visits | Number_of_Visits					14
Third threshold of therapy services required, visits | Number_of_Visits					20
Historical collection rate from Medicare					99.00%
Episodes in progress that begin during reporting period, days | D					60
Hospice Medicare revenue rate accounted for routine care					99.00%	99.00%	98.00%
Percentage of patient receivables outstanding					10.00%
Percentage of Patient Receivables Outstanding Over Ten Percent	10.10%				10.10%
Minimum days for accounts receivable outstanding to be fully reserved | D					365
Portion of accounts receivable derived from Medicare					61.00%	64.00%
Revenue adjustment to Medicare revenue					$ 7,900	$ 6,100	$ 5,100
Rate of request for anticipated payment submitted for the initial episode of care					60.00%
Rate of request for anticipated payment submitted for subsequent episodes of care					50.00%
Maximum days to submit final bill from the start of episode | D					120
Maximum days to submit final bill from the date the request for anticipated payment was paid | D					60
Asset Impairment Charges					$ 4,432	77,268	3,107
Income Taxes [Line Items]
Net deferred tax assets (liabilities)	$ 107,900	$ 125,200			107,900	125,200
Property Plant And Equipment [Line Items]
Internally developed computer software							75,800
Depreciation					17,200	20,000	28,000
Debt Issuance Costs [Line Items]
Amortization of deferred debt issuance costs/debt discount					740	959	797
Write-off of deferred debt issuance cost			$ 2,500
Deferred debt issuance cost						2,400
Unamortized debt issuance costs	2,700	3,400			$ 2,700	3,400
Unamortized debt issuance costs, weighted average amortization period, years					3 years 8 months 12 days
Non-cash compensation					$ 16,401	11,824	5,597
Share-based compensation, tax benefit recognized					6,400	4,700	2,000
Advertising expense					7,800	6,900	4,700
AMS3 Homecare and Hospice [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Asset Impairment Charges				$ 75,200
Corporate Headquarters [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Asset Impairment Charges		2,100
Homecare Homebase [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Asset Impairment Charges	4,400
Home Health [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Asset Impairment Charges					0	0	1,600
Hospice [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Asset Impairment Charges					0	0	1,500
Deferred Debt Issuance Costs [Member]
Debt Issuance Costs [Line Items]
Amortization of deferred debt issuance costs/debt discount					$ 700	800	$ 700
Acquired Names [Member]
Goodwill and Intangible Assets [Line Items]
Estimated Useful Life of Intangible Assets					5 years
Noncompete Agreements [Member]
Goodwill and Intangible Assets [Line Items]
Estimated Useful Life of Intangible Assets					3 years
Cap Year Two Thousand Thirteen Through Two Thousand Sixteen [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Estimated amounts due back to Medicare	$ 800	$ 1,400			$ 800	$ 1,400