Legal Proceedings (Details) (Litigation Related to Information Security Issues [Member], USD $)	3 Months Ended
	Mar. 31, 2013 employees_members_providers actions	Mar. 28, 2011 claims	Mar. 18, 2011 Customers
Litigation Related to Information Security Issues [Member]
Litigation and Investigations Related to Unaccounted-for Server Drives [Abstract]
Number of pending litigations	3
Total number of people with information on drives	2,000,000
Period of free credit monitoring services	2 years
Remaining actions currently pending, after consolidation	2
Estimated putative class members			800,000
Damages sought for each class member			$ 1,000
Number of named plaintiffs' claims on which arbitration was requested		2
Number of motions for arbitration granted		1