Indebtedness - Schedule of Notes Maturity (Details) $ in Millions	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Unsecured senior notes, net	$ 2,459
Unsecured Senior Notes
Debt Instrument [Line Items]
2019	0
2020	0
2021	592
2022	206
2023	950
Thereafter	750
Total	2,498
Unsecured debt issuance costs	(39)
Unsecured senior notes, net	$ 2,459

Face (par) amount of debt instrument at time of issuance.

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