Revenue and Accounts Receivable Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	$ 263,938
Less: allowance for doubtful accounts	(2,484)	$ (43,961)
Accounts receivable, net	261,454
Medicaid
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	101,310
Managed care
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	53,825
Medicare
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	47,367
Private Pay and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	61,436
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	311,321	309,029
Less: allowance for doubtful accounts	(49,867)	(43,961)
Accounts receivable, net	261,454	265,068
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Medicaid
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	117,227	119,441
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Managed care
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	67,150	68,930
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Medicare
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	54,428	55,667
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Private Pay and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	$ 72,516	$ 64,991