Business Combinations - Narrative (Details) $ in Thousands							9 Months Ended
	Jun. 26, 2017 USD ($)	Jun. 12, 2017 USD ($)	Jun. 09, 2017 USD ($)	Jun. 01, 2017 USD ($)	Mar. 01, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) company	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Number of companies | company							8
Payment to acquire assets							$ 42,513
Assets acquired							25,634
Tangible assets							1,943
Goodwill							288,590	$ 273,660
Loma Linda
Business Acquisition [Line Items]
Payment to acquire assets						$ 2,700	2,741
Assets acquired						2,200	2,225
Tangible assets							33
Rainbow ADH
Business Acquisition [Line Items]
Payment to acquire assets					$ 24,600		24,630
Assets acquired					13,300		13,260
Tangible assets					1,500		1,497
Goodwill					9,900
JLH
Business Acquisition [Line Items]
Payment to acquire assets				$ 1,500			1,497
Assets acquired							1,301
Tangible assets							60
Goodwill				100
Mi Casa
Business Acquisition [Line Items]
Payment to acquire assets			$ 4,900				4,940
Assets acquired			3,000				2,960
Tangible assets							59
Goodwill			1,900
Harbor Rehab
Business Acquisition [Line Items]
Payment to acquire assets		$ 2,100					2,103
Assets acquired		1,600					1,642
Tangible assets							0
Goodwill		500
Brockton Stoughton ADH
Business Acquisition [Line Items]
Payment to acquire assets	$ 6,300						6,250
Assets acquired	4,000						4,000
Tangible assets							195
Goodwill	2,100
Hope Homes and Res-Care
Business Acquisition [Line Items]
Payment to acquire assets							$ 400
Agency contracts | Loma Linda
Business Acquisition [Line Items]
Assets acquired						$ 1,700
Useful life						12 years
Agency contracts | Rainbow ADH
Business Acquisition [Line Items]
Assets acquired					$ 11,300
Useful life					12 years
Agency contracts | JLH
Business Acquisition [Line Items]
Assets acquired				$ 1,300
Useful life				12 years
Agency contracts | Mi Casa
Business Acquisition [Line Items]
Assets acquired			$ 2,500
Useful life			12 years
Agency contracts | Harbor Rehab
Business Acquisition [Line Items]
Assets acquired		$ 1,100
Useful life		12 years
Agency contracts | Brockton Stoughton ADH
Business Acquisition [Line Items]
Assets acquired	$ 3,400
Useful life	12 years
Licenses permits and other | Rainbow ADH
Business Acquisition [Line Items]
Assets acquired					$ 2,000
Useful life					10 years
I/DD | Loma Linda
Business Acquisition [Line Items]
Goodwill						$ 500