Segment And Geographic Information (Schedule Of Geographic Distributions Of Revenues, Equity In Earnings Of Affiliates, Adjusted Segment EBITDA, Depreciation And Amortization, Assets And Goodwill) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Revenues	$ 8,062	$ 7,258		$ 24,579	$ 21,913
Equity in earnings of affiliates	(6)	(68)		(26)	(217)
Adjusted segment EBITDA	1,533	1,412		4,925	4,422
Depreciation and amortization	417	362		1,254	1,078
Adjusted segment EBITDA	1,533	1,412		4,925	4,422
Depreciation and amortization	417	362		1,254	1,078
Interest expense	446	519		1,336	1,572
Losses (gains) on sales of facilities	(7)	2		(4)	3
Losses on retirement of debt		406	(75)		481
Termination of management agreement					181
Income before income taxes	677	123		2,339	1,107
National Group [Member]
Segment Reporting Information [Line Items]
Revenues	3,108	3,002		9,539	9,119
Equity in earnings of affiliates	1	(3)		(6)	(5)
Adjusted segment EBITDA	630	587		2,031	1,835
Depreciation and amortization	136	129		419	381
Adjusted segment EBITDA	630	587		2,031	1,835
Depreciation and amortization	136	129		419	381
Southwest Group [Member]
Segment Reporting Information [Line Items]
Revenues	2,864	2,239		8,618	6,724
Equity in earnings of affiliates	(6)	(64)		(20)	(212)
Adjusted segment EBITDA	656	552		2,049	1,714
Depreciation and amortization	151	111		447	332
Adjusted segment EBITDA	656	552		2,049	1,714
Depreciation and amortization	151	111		447	332
Central Group [Member]
Segment Reporting Information [Line Items]
Revenues	1,765	1,730		5,429	5,216
Equity in earnings of affiliates				(1)
Adjusted segment EBITDA	323	298		1,052	949
Depreciation and amortization	90	86		265	263
Adjusted segment EBITDA	323	298		1,052	949
Depreciation and amortization	90	86		265	263
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Revenues	325	287		993	854
Equity in earnings of affiliates	(1)	(1)		1
Adjusted segment EBITDA	(76)	(25)		(207)	(76)
Depreciation and amortization	40	36		123	102
Adjusted segment EBITDA	(76)	(25)		(207)	(76)
Depreciation and amortization	$ 40	$ 36		$ 123	$ 102