Long-Term Debt and Notes Payable - Select Credit Facilities (Details) - Select Excluding Concentra - Credit facility - USD ($)	Mar. 22, 2018	Mar. 06, 2017
2017 Select Credit Facilities
Long-term debt and notes payable
Current borrowing capacity		$ 1,600,000,000
Term loan | 2017 Select Credit Facilities
Long-term debt and notes payable
Aggregate principal amount		$ 1,150,000,000
Term loan | 2017 Select Credit Facilities | Adjusted LIBO
Long-term debt and notes payable
Interest rate margin (as a percent)		3.50%
Term loan | 2017 Select Credit Facilities | Adjusted LIBO Rate floor
Long-term debt and notes payable
Interest rate margin (as a percent)		1.00%
Term loan | 2017 Select Credit Facilities | Alternate Base Rate
Long-term debt and notes payable
Interest rate margin (as a percent)		2.50%
Term loan | 2017 Select Credit Facilities | Alternate Base Rate floor
Long-term debt and notes payable
Interest rate margin (as a percent)		2.00%
Term loan | 2017 Select Credit Facilities Amendment | Adjusted LIBO | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)	2.50%
Term loan | 2017 Select Credit Facilities Amendment | Adjusted LIBO | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)	2.75%
Term loan | 2017 Select Credit Facilities Amendment | Alternate Base Rate | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)	1.50%
Term loan | 2017 Select Credit Facilities Amendment | Alternate Base Rate | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)	1.75%
Revolving facility | 2017 Select Credit Facilities
Long-term debt and notes payable
Current borrowing capacity		$ 450,000,000
Revolving facility | 2017 Select Credit Facilities | Adjusted LIBO | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)		3.00%
Revolving facility | 2017 Select Credit Facilities | Adjusted LIBO | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)		3.25%
Revolving facility | 2017 Select Credit Facilities | Alternate Base Rate | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)		2.00%
Revolving facility | 2017 Select Credit Facilities | Alternate Base Rate | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)		2.25%
Revolving facility | 2017 Select Credit Facilities Amendment | Adjusted LIBO | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)	2.50%
Revolving facility | 2017 Select Credit Facilities Amendment | Adjusted LIBO | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)	2.75%
Revolving facility | 2017 Select Credit Facilities Amendment | Alternate Base Rate | Minimum
Long-term debt and notes payable
Interest rate margin (as a percent)	1.50%
Revolving facility | 2017 Select Credit Facilities Amendment | Alternate Base Rate | Maximum
Long-term debt and notes payable
Interest rate margin (as a percent)	1.75%
Letter of credit | 2017 Select Credit Facilities
Long-term debt and notes payable
Current borrowing capacity		$ 75,000,000