Borrowings (Credit Facilities Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
CSC’s stockholders’ equity, excluding accumulated other comprehensive income	$ 11,600,000,000
Commercial paper [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,500,000,000
Line of credit facility, current borrowing capacity	800,000,000
Commercial Paper Notes, amount outstanding	0	0
Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	240,000,000
Group of 12 banks [Member] | Line of credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	800,000,000
Unsecured credit facility, expiration date	Jun. 01, 2015
Minimum level of stockholders' equity required under credit facility	7,800,000,000
Line of credit	0	0
Group of banks [Member] | Line of credit [Member]
Line of Credit Facility [Line Items]
Line of credit	0	0
Group of 5 banks [Member] | Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Line of credit	0	0
Group of 5 banks [Member] | Charles Schwab & Co., Inc. [Member] | Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	225,000,000
1 bank [Member] | Standby letters of credit [Member]
Line of Credit Facility [Line Items]
Line of credit	0
1 bank [Member] | Standby letters of credit [Member] | OptionsXpress, Inc. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity	$ 15,000,000
Maximum [Member] | Commercial paper [Member]
Line of Credit Facility [Line Items]
Debt instrument term	270 days