Accounting Policies - Schedule of Revenues from Third Party Payers and Uninsured (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									$ 34,109	$ 33,272	$ 29,846
Uninsured									2,677	2,580	1,846
Other									1,254	931	814
Revenues before provision for doubtful accounts									38,040	36,783	32,506
Provision for doubtful accounts									(3,858)	(3,770)	(2,824)
Revenues	8,836	8,456	8,450	8,440	8,434	8,062	8,112	8,405	34,182	33,013	29,682
Revenues from third party payers, ratio									99.80%	100.70%	100.60%
Uninsured Ratio									7.80%	7.80%	6.20%
Other Ratio									3.70%	2.80%	2.70%
Revenues before provision for doubtful accounts, ratio									111.30%	111.30%	109.50%
Provision for doubtful accounts Ratio									(11.30%)	(11.30%)	(9.50%)
Revenues ratio from third party payers									100.00%	100.00%	100.00%
Medicare [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									7,951	8,292	7,653
Revenues from third party payers, ratio									23.30%	25.10%	25.80%
Managed Medicare [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									3,279	2,954	2,442
Revenues from third party payers, ratio									9.60%	8.90%	8.20%
Medicaid [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									1,480	1,464	1,845
Revenues from third party payers, ratio									4.30%	4.40%	6.20%
Managed Medicaid [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									1,570	1,504	1,265
Revenues from third party payers, ratio									4.60%	4.60%	4.30%
Managed Care and Other Insurers [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									18,654	17,998	15,703
Revenues from third party payers, ratio									54.60%	54.50%	52.90%
International (Managed Care and Other Insurers) [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues from third party payers									$ 1,175	$ 1,060	$ 938
Revenues from third party payers, ratio									3.40%	3.20%	3.20%