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Leases - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Leases
Cumulative effect of accounting change	$ 2,000,000	$ 176,000,000
Rent expense	173,000,000	166,000,000
Retained earnings
Leases
Cumulative effect of accounting change	$ 2,000,000	$ 175,000,000
Minimum | ASC 842 | Retained earnings
Leases
Cumulative effect of accounting change			$ 0

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- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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- Definition

[Line Items] for Leases [Table]

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