Schedule I - Parent Company Financial Information (Condensed Balance Sheets) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 1,306	$ 1,377	$ 1,673	$ 1,613
Investment securities	8,001	7,743
Other current assets	1,670	1,027
Total current assets	11,710	11,181
Property and equipment, net	1,098	912
Other long-term assets	1,685	1,165
Total assets	19,979	17,708
Current liabilities:
Book overdraft	324	306
Total current liabilities	6,375	6,056
Long-term debt	2,611	1,659
Other long-term liabilities	288	267
Total liabilities	11,132	9,645
Commitments and contingencies
Stockholders' equity:
Preferred stock, $1 par; 10,000,000 shares authorized; none issued	0	0
Common stock, $0.16 2/3 par; 300,000,000 shares authorized; 194,470,820 shares issued in 2012 and 193,230,310 shares issued in 2011	32	32
Capital in excess of par value	2,101	1,938
Retained earnings	7,881	6,825
Accumulated other comprehensive income	386	303
Treasury stock, at cost, 36,138,955 shares in 2012 and 29,225,996 shares in 2011	(1,553)	(1,035)
Total stockholders' equity	8,847	8,063	6,924	5,776
Total liabilities and stockholders' equity	19,979	17,708
Parent Company
Current assets:
Cash and cash equivalents	151	187	314	346
Investment securities	195	307
Receivable from operating subsidiaries	523	572
Other current assets	97	75
Total current assets	966	1,141
Property and equipment, net	660	543
Investments in subsidiaries	12,136	9,971
Other long-term assets	69	55
Total assets	13,831	11,710
Current liabilities:
Payable to operating subsidiaries	1,713	1,364
Current portion of notes payable to operating subsidiaries	28	28
Book overdraft	52	44
Other current liabilities	376	400
Total current liabilities	2,169	1,836
Long-term debt	2,611	1,623
Notes payable to operating subsidiaries	9	9
Other long-term liabilities	195	179
Total liabilities	4,984	3,647
Commitments and contingencies
Stockholders' equity:
Preferred stock, $1 par; 10,000,000 shares authorized; none issued	0	0
Common stock, $0.16 2/3 par; 300,000,000 shares authorized; 194,470,820 shares issued in 2012 and 193,230,310 shares issued in 2011	32	32
Capital in excess of par value	2,101	1,938
Retained earnings	7,881	6,825
Accumulated other comprehensive income	386	303
Treasury stock, at cost, 36,138,955 shares in 2012 and 29,225,996 shares in 2011	(1,553)	(1,035)
Total stockholders' equity	8,847	8,063
Total liabilities and stockholders' equity	$ 13,831	$ 11,710