| **Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions** | Total    | Common Stock | Additional Paid in Capital | Accumulated Other Comprehensive Loss | Treasury Stock at Cost | Retained Earnings | Non-controlling Interests |
|-----------------------------------------------------------------------------|----------|--------------|----------------------------|--------------------------------------|------------------------|-------------------|---------------------------|
| Shareholders Equity, Beginning Balance at Dec. 31, 2014                     | $ 10,325 | $ 4          | $ 3,624                    | $ (90)                               | $ (671)                | $ 7,458           | $ 0                       |
| **Increase (Decrease) in Stockholders' Equity [Roll Forward]**              |     |         |                       |                                 |                   |              |                      |
| Net (Loss) Income                                                           | (2,441)  |         |                       |                                 |                   | (2,441)           |                      |
| Merger and Acquisition                                                      | 1,529    | 1            | 1,528                      |                                 |                   |              |                      |
| Stock-based Compensation                                                    | 86       |         | 86                         |                                 |                   |              |                      |
| Exercise of Stock Options                                                   | 8        |         | 8                          |                                 |                   |              |                      |
| Dividends                                                                   | (291)    |         |                       |                                 |                   | (291)             |                      |
| Issuance of Stock, Net of Offering Costs                                    | 1,112    |         | 1,112                      |                                 |                   |              |                      |
| Net Change in Other                                                         | 42       |         | 2                          | 57                                   | (17)                   |              |                      |
| Shareholders Equity, Ending Balance at Dec. 31, 2015                        | 10,370   | 5            | 6,360                      | (33)                                 | (688)                  | 4,726             | 0                         |
| **Increase (Decrease) in Stockholders' Equity [Roll Forward]**              |     |         |                       |                                 |                   |              |                      |
| Net (Loss) Income                                                           | (985)    |         |                       |                                 |                   | (998)             | 13                        |
| Stock-based Compensation                                                    | 68       |         | 68                         |                                 |                   |              |                      |
| Exercise of Stock Options                                                   | 24       |         | 24                         |                                 |                   |              |                      |
| Dividends                                                                   | (172)    |         |                       |                                 |                   | (172)             |                      |
| Issuance of Stock, Net of Offering Costs                                    | 299      |         |                       |                                 |                   |              | 299                       |
| Net Change in Other                                                         | (4)      |         | (2)                        | 2                                    | (4)                    |              |                      |
| Shareholders Equity, Ending Balance at Dec. 31, 2016                        | 9,600    | 5            | 6,450                      | (31)                                 | (692)                  | 3,556             | 312                       |
| **Increase (Decrease) in Stockholders' Equity [Roll Forward]**              |     |         |                       |                                 |                   |              |                      |
| Net (Loss) Income                                                           | (1,050)  |         |                       |                                 |                   | (1,118)           | 68                        |
| Merger and Acquisition                                                      | 1,851    |         | 1,876                      |                                 | (25)                   |              |                      |
| Stock-based Compensation                                                    | 100      |         | 100                        |                                 |                   |              |                      |
| Exercise of Stock Options                                                   | 10       |         | 10                         |                                 |                   |              |                      |
| Dividends                                                                   | (190)    |         |                       |                                 |                   | (190)             |                      |
| Issuance of Stock, Net of Offering Costs                                    | 312      |         |                       |                                 |                   |              | 312                       |
| Distributions to Noncontrolling Interest Owners                             | (28)     |         |                       |                                 |                   |              | (28)                      |
| Net Change in Other                                                         | 14       |         | 2                          | 1                                    | (8)                    |              | 19                        |
| Shareholders Equity, Ending Balance at Dec. 31, 2017                        | $ 10,619 | $ 5          | $ 8,438                    | $ (30)                               | $ (725)                | $ 2,248           | $ 683                     |

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| - Definition
Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
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Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders.
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| - Definition
Amount after tax and reclassification adjustments of other comprehensive income (loss).
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| - Definition
The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.
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| - Definition
Value of stock issued pursuant to acquisitions during the period.
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| - Definition
Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.
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Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.
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| - Definition
Value of stock issued as a result of the exercise of stock options.
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| - Definition
Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.
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