Investments (Number of Securities Included in Loss Position of Current and Noncurrent Investments) (Details)	Mar. 31, 2015 Securities
Current [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	352
12 Months or More	67
Total, number of securities	419
Current [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	118
12 Months or More	21
Total, number of securities	139
Current [Member] | U.S. Government and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	3
12 Months or More	0
Total, number of securities	3
Current [Member] | Obligations of States and Other Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	129
12 Months or More	16
Total, number of securities	145
Current [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	102
12 Months or More	30
Total, number of securities	132
Noncurrent [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	10
12 Months or More	1
Total, number of securities	11
Noncurrent [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	0
12 Months or More	1
Total, number of securities	1
Noncurrent [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	10
12 Months or More	0
Total, number of securities	10