Investments (Number of Securities Included in Loss Position of Current and Noncurrent Investments) (Details) (Current [Member])	Dec. 31, 2012 Securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months number of securities	158
12 months or more number of securities	4
Total number of securities	162
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months number of securities	25
12 months or more number of securities	3
Total number of securities	28
U.S. government and agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months number of securities	1
12 months or more number of securities	0
Total number of securities	1
Obligations of states and other political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months number of securities	82
12 months or more number of securities	1
Total number of securities	83
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months number of securities	50
12 months or more number of securities	0
Total number of securities	50