Fair Value (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 282	$ 280
Trading securities	58	55
Total assets	340	335
Contingent Value Right (CVR)	4	6
CVR-related legal liability	271	265
Fair value of interest rate swap agreements	70	68
Total liabilities	345	339
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	157	151
Trading securities	58	55
Total assets	215	206
Contingent Value Right (CVR)	4	6
Total liabilities	4	6
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	125	129
Total assets	125	129
Fair value of interest rate swap agreements	70	68
Total liabilities	70	68
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
CVR-related legal liability	271	265
Total liabilities	$ 271	$ 265