Business Segments - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 627,253	$ 589,613
Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 623,276	$ 585,951
Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	100.00%	100.00%
Medicaid | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 231,358	$ 224,195
Medicaid | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	37.10%	38.30%
Medicare | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 190,303	$ 155,584
Medicare | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	30.50%	26.60%
Medicaid — skilled | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 39,993	$ 36,009
Medicaid — skilled | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	6.50%	6.10%
Total Medicaid and Medicare | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 461,654	$ 415,788
Total Medicaid and Medicare | Revenue Benchmark | Customer Concentration Risk
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	74.10%	71.00%
Total Medicaid and Medicare | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	74.10%	71.00%
Managed care | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 108,345	$ 102,029
Managed care | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	17.40%	17.40%
Private and other | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 53,277	$ 68,134
Private and other | Revenue Benchmark | Customer Concentration Risk | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration risk	8.50%	11.60%
Operating Segments | Transitional and Skilled Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 601,036	$ 558,304
Operating Segments | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	601,036	558,304
Operating Segments | Medicaid | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	227,741	220,969
Operating Segments | Medicare | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	190,303	155,584
Operating Segments | Medicaid — skilled | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	39,993	36,009
Operating Segments | Total Medicaid and Medicare | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	458,037	412,562
Operating Segments | Managed care | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	108,345	102,029
Operating Segments | Private and other | Transitional and Skilled Services | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	34,654	43,713
All Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	22,240	27,647
All Other | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	22,240	27,647
All Other | Medicaid | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	3,617	3,226
All Other | Medicare | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	0	0
All Other | Medicaid — skilled | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	0	0
All Other | Total Medicaid and Medicare | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	3,617	3,226
All Other | Managed care | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	0	0
All Other | Private and other | Service revenue
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenue	$ 18,623	$ 24,421