Regulatory Capital Matters - Additional Information (Details) - USD ($) $ in Billions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer	1.875%	1.25%	0.625%
Capital conservation buffer description	The capital conservation buffers for 2016, 2017 and 2018 are 0.625%, 1.25% and 1.875%, respectively.
Minimum
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital required to be well capitalized	$ 3

The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 505
-Section 50
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-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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-Name Accounting Standards Codification
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Description of the regulatory requirements for capital adequacy purposes.

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