Intangible Assets (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Indefinite-lived intangible assets:    
Goodwill $ 1,652,005 $ 1,642,083
Total 1,724,645 1,714,602
Trademarks    
Indefinite-lived intangible assets:    
Intangible assets excluding goodwill 57,709 57,709
Weighted average time until next renewal 5 years 2 months 12 days  
Certificates of need    
Indefinite-lived intangible assets:    
Intangible assets excluding goodwill 12,848 12,727
Accreditations    
Indefinite-lived intangible assets:    
Intangible assets excluding goodwill $ 2,083 $ 2,083
Weighted average time until next renewal 1 year 6 months