v3.19.1

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Other Commitments [Line Items] |  |  |
Royalty Expense | $ 26 | $ 25 | $ 22
Guarantor Obligations, Current Carrying Value | 0 |  |
LTSA [Member] |  |  |
Unrecorded Unconditional Purchase Obligation |  |  |
Unrecorded Unconditional Purchase Obligation | 243 |  |
Electric Generation Equipment [Member] |  |  |
Other Commitments [Line Items] |  |  |
Operating Leases, Rent Expense, Net | 43 | 41 | 38
Office Equipment [Member] |  |  |
Other Commitments [Line Items] |  |  |
Operating Leases, Rent Expense, Net | 10 | $ 9 | $ 9
Operating Leases, Future Minimum Payments Due, Next Twelve Months | 6 |  |
Unrecorded Unconditional Purchase Obligation |  |  |
Operating Leases, Future Minimum Payments, Due in Two Years | 6 |  |
Operating Leases, Future Minimum Payments, Due in Three Years | 8 |  |
Operating Leases, Future Minimum Payments, Due in Four Years | 8 |  |
Operating Leases, Future Minimum Payments, Due in Five Years | 7 |  |
Operating Leases, Future Minimum Payments, Due Thereafter | 18 |  |
Operating Leases, Future Minimum Payments Due | 53 |  |
Minimum [Member] | LTSA [Member] |  |  |
Unrecorded Unconditional Purchase Obligation |  |  |
Unrecorded Unconditional Purchase Obligation | $ 18 |  |
Unrecorded Unconditional Purchase Obligation, Term | 1 year |  |
Maximum [Member] | LTSA [Member] |  |  |
Unrecorded Unconditional Purchase Obligation |  |  |
Unrecorded Unconditional Purchase Obligation, Term | 19 years |  |

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