v3.8.0.1

Fair Value Measurements - Fair Value Measurements By Level for Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Assets |  |
Cash and cash equivalents | $ 4,072 | $ 3,930
Investments available for sale: |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 195 | 236
Corporate securities | 2,210 | 1,932
Municipal securities | 2,087 | 1,733
Asset-backed securities | 437 | 317
Total investments | 5,532 | 4,771
Restricted deposits available for sale: |  |
Cash and cash equivalents | 17 | 6
Certificates of deposit | 4 | 5
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 114 | 127
Total restricted deposits | 135 | 138
Other long-term assets: |  |
Interest rate swap agreements | 1 | 4
Total assets at fair value | 9,740 | 8,843
Liabilities |  |
Interest rate swap agreements | 72 | 62
Total liabilities at fair value | 72 | 62
Residential mortgage-backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 332 | 215
Commercial mortgage- backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 271 | 338
Level I |  |
Assets |  |
Cash and cash equivalents | 4,072 | 3,930
Investments available for sale: |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 195 | 221
Corporate securities | 0 | 0
Municipal securities | 0 | 0
Asset-backed securities | 0 | 0
Total investments | 195 | 221
Restricted deposits available for sale: |  |
Cash and cash equivalents | 17 | 6
Certificates of deposit | 4 | 5
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 114 | 127
Total restricted deposits | 135 | 138
Other long-term assets: |  |
Interest rate swap agreements | 0 | 0
Total assets at fair value | 4,402 | 4,289
Liabilities |  |
Interest rate swap agreements | 0 | 0
Total liabilities at fair value | 0 | 0
Level I | Residential mortgage-backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 0 | 0
Level I | Commercial mortgage- backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 0 | 0
Level II |  |
Assets |  |
Cash and cash equivalents | 0 | 0
Investments available for sale: |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 0 | 15
Corporate securities | 2,210 | 1,932
Municipal securities | 2,087 | 1,733
Asset-backed securities | 437 | 317
Total investments | 5,337 | 4,550
Restricted deposits available for sale: |  |
Cash and cash equivalents | 0 | 0
Certificates of deposit | 0 | 0
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 0 | 0
Total restricted deposits | 0 | 0
Other long-term assets: |  |
Interest rate swap agreements | 1 | 4
Total assets at fair value | 5,338 | 4,554
Liabilities |  |
Interest rate swap agreements | 72 | 62
Total liabilities at fair value | 72 | 62
Level II | Residential mortgage-backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 332 | 215
Level II | Commercial mortgage- backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 271 | 338
Level III |  |
Assets |  |
Cash and cash equivalents | 0 | 0
Investments available for sale: |  |
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 0 | 0
Corporate securities | 0 | 0
Municipal securities | 0 | 0
Asset-backed securities | 0 | 0
Total investments | 0 | 0
Restricted deposits available for sale: |  |
Cash and cash equivalents | 0 | 0
Certificates of deposit | 0 | 0
U.S. Treasury securities and obligations of U.S. government corporations and agencies | 0 | 0
Total restricted deposits | 0 | 0
Other long-term assets: |  |
Interest rate swap agreements | 0 | 0
Total assets at fair value | 0 | 0
Liabilities |  |
Interest rate swap agreements | 0 | 0
Total liabilities at fair value | 0 | 0
Level III | Residential mortgage-backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | 0 | 0
Level III | Commercial mortgage- backed securities |  |
Investments available for sale: |  |
Mortgage-backed securities | $ 0 | $ 0

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