Accounts Receivable - Table 1 (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Accounts Receivable, Net, Current
Patient accounts receivable, net of allowance for doubtful accounts of $22.2 million in 2014; $23.1 million in 2013	$ 309.3	$ 249.4
Other accounts receivable	13.9	12.4
Accounts receivable, net, current	323.2	261.8
Noncurrent patient accounts receivable, net of allowance for doubtful accounts of $20.8 million in 2014; $10.0 million in 2013	51.4	16.6
Accounts receivable, net	374.6	278.4
Allowance for Doubtful Accounts [Abstract]
Allowance for doubtful accounts receivable, current	22.2	23.1
Allowance for doubtful accounts receivable, noncurrent	$ 20.8	$ 10.0