Commitments and Contingencies (Professional Liability Claims Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Malpractice Insurance [Line Items]
Malpractice loss contingency, historical claims period used by actuary to estimate liability	20 years
Malpractice Loss Contingency, Discount Rate	1.70%	1.60%	1.20%
Malpractice Loss Contingency, Accrual, Discounted	$ 924	$ 644
Malpractice Loss Contingency, Accrual, Undiscounted	964	687
Malpractice Loss Contingency, Accrual, Discounted, Current	164	104
Malpractice loss contingency, settled claims as percent of total liability	1.00%
Professional and general liability self-insured claims reported prior to June 1, 2002, per occurrence [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	1
Professional and general liability self-insured reported from June 1, 2002 through June 1, 2003, per occurrence [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	2
Professional and general liability self-insured reported from June 1, 2003 and before June 1, 2005, per occurrence [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	4
Professional and general liability self-insured claims reported on or after June 1, 2005, per occurrence [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	5
Professional and general liability claims reported on or after June 1, 2014 [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	10
Professional and general liability claims reported on or after June 1, 2003 [Member]
Malpractice Insurance [Line Items]
Malpractice Insurance, Maximum Coverage Per Incident	95
Professional and general liability claims incurred and reported after January 1, 2008 [Member]
Malpractice Insurance [Line Items]
Malpractice Insurance, Maximum Coverage Per Incident	145
Professional and general liability claims incurred and reported after January 1, 2010 [Member]
Malpractice Insurance [Line Items]
Malpractice Insurance, Maximum Coverage Per Incident	195
Professional and general liability self-insured claims under certain policy terms until Company total aggregate coverage is met if first aggregate layer becomes fully utilized [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	10
Triad professional and general liability self-insured claims during 2007 [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	10
Minimum [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, average lag period from occurence to settlement	4 years
Malpractice loss contingency, self-insured retention	10
Minimum [Member] | Triad professional and general liability self-insured claims after December 31, 2006 [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	1
Maximum [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, average lag period from occurence to settlement	5 years
Malpractice loss contingency, self-insured retention	15
Maximum [Member] | Triad professional and general liability self-insured claims after December 31, 2006 [Member]
Malpractice Insurance [Line Items]
Malpractice loss contingency, self-insured retention	$ 5