Leases (Narrative) (Details) - USD ($) $ in Billions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2019 |
|
| Lessee, Lease, Description [Line Items] | |||
| Weighted average remaining lease term | 10 years | ||
| Weighted average discount rate | 2.80% | ||
| Operating leases not yet commenced, future minimum lease payments | $ 7.4 | ||
| Rent expense under operating leases | $ 1.3 | $ 1.1 | |
| Minimum | |||
| Lessee, Lease, Description [Line Items] | |||
| Operating lease, non-cancelable lease term | 1 year | ||
| Finance lease, non-cancelable lease term | 1 year | ||
| Maximum | |||
| Lessee, Lease, Description [Line Items] | |||
| Operating lease, non-cancelable lease term | 25 years | ||
| Finance lease, non-cancelable lease term | 25 years | ||