Variable Interest Entities - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) structured_note_vehicle	Dec. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Maximum exposure to loss	$ 3,541	$ 3,457
Number of structured note vehicles unwound | structured_note_vehicle	1
Gain from make-whole payment from third-party investment guarantor	$ 11
Structured note vehicles [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Maximum exposure to loss	3,013	$ 3,003
Trading Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment in structured note vehicle	$ 1,081