Fair Value Measurements (Details) - USD ($) |
Dec. 31, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
---|---|---|---|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Carrying amount of liabilities | $ 8,711,000,000 | $ 9,709,000,000 | |
Transfers between level 1, level 2, or level 3 of the fair value hierarchy | 0 | $ 0 | |
Fair malue, measurements, recurring | Fair value, inputs, level 2 | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Estimated fair values of liabilities | 9,000,000,000 | 10,400,000,000 | |
Fair malue, measurements, recurring | Fair value, inputs, level 1 | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Investments in money market funds, time deposits and repurchase agreements | $ 1,900,000,000 | $ 4,200,000,000 |