Supplemental Disclosures to Consolidated Statements of Cash Flows (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Supplemental Disclosures to Consolidated Statements of Cash Flow [Abstract] | |||
| Fair value of assets acquired | $ 956 | $ 154 | |
| Intangible assets not subject to amortization | 1,577 | $ 7 | 1,791 |
| Intangible assets subject to amortization | 651 | (40) | 837 |
| Net liabilities assumed | (977) | (214) | |
| Deferred tax assets (liabilities) | (281) | 33 | (637) |
| Fair value of equity consideration | 1,948 | 1,087 | |
| Cash paid (received) for acquisitions, net of cash acquired | (22) | 844 | |
| Cash paid for interest | 343 | 354 | 374 |
| Cash paid for income taxes | $ 158 | $ 204 | $ 318 |