Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 segment	Mar. 31, 2012
Segment information
Expenses	$ 3,731	$ 3,956
OPERATING INCOME	782	654
Number of operating segments	4
Operating segments
Segment information
Revenues	4,256	4,344
Expenses	1,945	2,020
OPERATING INCOME	2,311	2,324
Margin percentage	54.30%	53.50%
Consumer
Segment information
Revenues	1,511	1,564
Expenses	526	567
OPERATING INCOME	985	997
Margin percentage	65.20%	63.70%
Business
Segment information
Revenues	1,504	1,508
Expenses	881	910
OPERATING INCOME	623	598
Margin percentage	41.40%	39.70%
Wholesale
Segment information
Revenues	907	962
Expenses	274	312
OPERATING INCOME	633	650
Margin percentage	69.80%	67.60%
Data Hosting
Segment information
Revenues	334	310
Expenses	264	231
OPERATING INCOME	$ 70	$ 79
Margin percentage	21.00%	25.50%