Investments (Number of Securities Included in Loss Position of Current and Noncurrent Investments) (Details) (Current [Member])	Mar. 31, 2013 Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than one year	243
Number of securities, one year or greater	6
Total, number of securities	249
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than one year	44
Number of securities, one year or greater	4
Total, number of securities	48
U.S. Government and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than one year	1
Number of securities, one year or greater	0
Total, number of securities	1
Obligations of States and Other Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than one year	137
Number of securities, one year or greater	1
Total, number of securities	138
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than one year	61
Number of securities, one year or greater	1
Total, number of securities	62