Income Taxes (Details Textuals) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2016 |
Jun. 30, 2015 |
Jun. 30, 2016 |
Jun. 30, 2015 |
|
| Income Taxes (Textuals) | ||||
| Unrecognized tax benefits as a result of potential resolutions of prior years' tax | $ 237 | $ 237 | ||
| Unrecognized tax benefits, amounts recorded to equity | $ 21 | $ 21 | ||
| Actual tax rates | 33.20% | 33.90% | 33.80% | 34.00% |
| Internal Revenue Service (IRS) [Member] | Earliest Year [Member] | ||||
| Income Tax Contingency [Line Items] | ||||
| Open tax years by major tax jurisdiction | 2008 | |||
| Internal Revenue Service (IRS) [Member] | Latest Year [Member] | ||||
| Income Tax Contingency [Line Items] | ||||
| Open tax years by major tax jurisdiction | 2014 | |||