Leasing Leasing (Sales-type and Direct Financing Leases, Lease Receivable, Maturity) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Leases [Abstract]
Direct financing lease, net investment in lease	$ 494		$ 494		$ 439
Direct financing lease, present value of lease payments recorded as lease receivable	481		481		425
Direct financing lease, unguaranteed residual asset	13		13		$ 14
Direct financing lease, interest income	7	$ 5	19	$ 16
2019	43		43
2020	168		168
2021	144		144
2022	87		87
2023	53		53
2024 and thereafter	41		41
Total undiscounted cash flows	536		536
Direct financing leases, lease receivable, difference between undiscounted cash flows and discounted cash flows	$ (55)		$ (55)

Amount of interest income from net investment in direct financing lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 6A
-URI http://asc.fasb.org/extlink&oid=118952077&loc=SL77927221-108306

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 5
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981

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Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919379-209981

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Amount of net investment in direct financing lease.

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Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919391-209981

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in fourth fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in remainder of the fiscal year following latest fiscal year. Excludes interim and annual period when interim periods are reported on a rolling approach, from latest statement of financial position date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases after fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in third fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases in second fiscal year following latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.

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Amount of undiscounted lease receivable in excess of discounted receivable for sales-type and direct financing leases.

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