Fair Value Option Elected, Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Loans Receivable, Fair Value Disclosure	$ 255	$ 257
Trading Loans [Member]
Loans Receivable, Fair Value Disclosure	2,625	2,655
Aggregate Unpaid Principal Balance Under the Fair Value Option	(2,571)	(2,605)
Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables	54	50
Loans Held For Sale [Member]
Loans Receivable, Fair Value Disclosure	1,593	1,494
Aggregate Unpaid Principal Balance Under the Fair Value Option	(1,531)	(1,453)
Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables	62	41
Loans Held For Investment [Member]
Loans Receivable, Fair Value Disclosure	250	254
Aggregate Unpaid Principal Balance Under the Fair Value Option	(251)	(259)
Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status, Aggregated Difference	(2)	(2)
Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables	(1)	(5)
Long-Term Debt [Domain]
Obligations, Fair Value Disclosure	975	973
Aggregate Unpaid Principal Balance Under the Fair Value Option, Liability	907	907
Fair Value, Option, Aggregate Differences, Long-term Debt Instruments	68	66
Loans Held For Investment [Member]
Nonaccrual loans	5	3
Loans Held For Investment [Member] \| Aggregate Unpaid Principal Balance Under Fair Value Option
Nonaccrual loans	$ 7	$ 5

Aggregate Unpaid Principal Balance Under the Fair Value Option, Asset

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- Definition

Aggregate Unpaid Principal Balance Under the Fair Value Option, Liability

+ References

No definition available.

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- Definition

Fair value of obligations measured on a recurring basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of long-term debt instruments that have contractual principal amounts and for which the fair value option has been elected.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

+ Details

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- Definition

For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are in nonaccrual status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(3)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Glossary Loan
-URI http://asc.fasb.org/extlink&oid=6517073

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