v3.8.0.1

Fair Value Measurements (Tables) | 12 Months Ended
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Dec. 31, 2017
Fair Value Disclosures [Abstract] |
Fair Value Measurements By Level For Assets Measured At Fair Value On A Recurring Basis | The following table summarizes fair value measurements by level at December 31, 2017, for assets and liabilities measured at fair value on a recurring basis ($ in millions):
| Level I |  | Level II |  | Level III |  | Total
Assets |  |  |  |  |  |  |
Cash and cash equivalents | $ | 4,072 |  |  | $ | — |  |  | $ | — |  |  | $ | 4,072 |
Investments available for sale: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | $ | 195 |  |  | $ | — |  |  | $ | — |  |  | $ | 195 |
Corporate securities | — |  |  | 2,210 |  |  | — |  |  | 2,210 |
Municipal securities | — |  |  | 2,087 |  |  | — |  |  | 2,087 |
Asset-backed securities | — |  |  | 437 |  |  | — |  |  | 437 |
Residential mortgage-backed securities | — |  |  | 332 |  |  | — |  |  | 332 |
Commercial mortgage-backed securities | — |  |  | 271 |  |  | — |  |  | 271 |
Total investments | $ | 195 |  |  | $ | 5,337 |  |  | $ | — |  |  | $ | 5,532 |
Restricted deposits available for sale: |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 17 |  |  | $ | — |  |  | $ | — |  |  | $ | 17 |
Certificates of deposit | 4 |  |  | — |  |  | — |  |  | 4 |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 114 |  |  | — |  |  | — |  |  | 114 |
Total restricted deposits | $ | 135 |  |  | $ | — |  |  | $ | — |  |  | $ | 135 |
Other long-term assets: |  |  |  |  |  |  |
Interest rate swap agreements | $ | — |  |  | $ | 1 |  |  | $ | — |  |  | $ | 1 |
Total assets at fair value | $ | 4,402 |  |  | $ | 5,338 |  |  | $ | — |  |  | $ | 9,740 |
Liabilities |  |  |  |  |  |  |
Other long-term liabilities: |  |  |  |  |  |  |
Interest rate swap agreements | $ | — |  |  | $ | 72 |  |  | $ | — |  |  | $ | 72 |
Total liabilities at fair value | $ | — |  |  | $ | 72 |  |  | $ | — |  |  | $ | 72 |
The following table summarizes fair value measurements by level at December 31, 2016, for assets and liabilities measured at fair value on a recurring basis ($ in millions):
| Level I |  | Level II |  | Level III |  | Total
Assets |  |  |  |  |  |  |
Cash and cash equivalents | $ | 3,930 |  |  | $ | — |  |  | $ | — |  |  | $ | 3,930 |
Investments available for sale: |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | $ | 221 |  |  | $ | 15 |  |  | $ | — |  |  | $ | 236 |
Corporate securities | — |  |  | 1,932 |  |  | — |  |  | 1,932 |
Municipal securities | — |  |  | 1,733 |  |  | — |  |  | 1,733 |
Asset-backed securities | — |  |  | 317 |  |  | — |  |  | 317 |
Residential mortgage-backed securities | — |  |  | 215 |  |  | — |  |  | 215 |
Commercial mortgage-backed securities | — |  |  | 338 |  |  | — |  |  | 338 |
Total investments | $ | 221 |  |  | $ | 4,550 |  |  | $ | — |  |  | $ | 4,771 |
Restricted deposits available for sale: |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 6 |  |  | $ | — |  |  | $ | — |  |  | $ | 6 |
Certificates of deposit | 5 |  |  | — |  |  | — |  |  | 5 |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 127 |  |  | — |  |  | — |  |  | 127 |
Total restricted deposits | $ | 138 |  |  | $ | — |  |  | $ | — |  |  | $ | 138 |
Other long-term assets: |  |  |  |  |  |  |
Interest rate swap agreements | $ | — |  |  | $ | 4 |  |  | $ | — |  |  | $ | 4 |
Total assets at fair value | $ | 4,289 |  |  | $ | 4,554 |  |  | $ | — |  |  | $ | 8,843 |
Liabilities |  |  |  |  |  |  |
Other long-term liabilities: |  |  |  |  |  |  |
Interest rate swap agreements | $ | — |  |  | $ | 62 |  |  | $ | — |  |  | $ | 62 |
Total liabilities at fair value | $ | — |  |  | $ | 62 |  |  | $ | — |  |  | $ | 62 |

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- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19190-110258 + Details
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