Fair Value (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 271	$ 280
Trading securities	61	55
Total assets	332	335
Contingent Value Right (CVR)	2	6
CVR-related legal liability	261	265
Fair value of interest rate swap agreements	76	68
Total liabilities	339	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	155	151
Trading securities	61	55
Total assets	216	206
Contingent Value Right (CVR)	2	6
Total liabilities	2	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	116	129
Total assets	116	129
Fair value of interest rate swap agreements	76	68
Total liabilities	76	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	261	265
Total liabilities	$ 261	$ 265