Changes in Accounting Principle (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended	1 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jan. 31, 2012 Change in methods of valuing prescription drug inventories
Changes in Accounting Principle
Percentage of consolidated inventories affected by change in accounting principle	51.00%	51.00%
Effect of changes in accounting principle
Decrease in inventories			$ 146
Increase in current deferred income tax assets			57
Decrease in retained earnings			89
Increase in income from continuing operations and net income attributable to CVS Caremark	$ 20	$ 1
Increase in basic earnings per common share	$ 0.01
Increase in diluted earnings per common share	$ 0.02