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SECURITIES - Amortized Cost and Fair Value of Securities Available for Sale (Detail) - USD ($) $ in Millions | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 3,268 | $ 3,401
Gross Unrealized Gains | 23 | 5
Gross Unrealized Losses | (12) | (65)
Total securities available for sale, fair value | 3,279 | 3,341
US Government Agencies [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 172 | 188
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | (1)
Total securities available for sale, fair value | 172 | 187
U.S. Government-Sponsored Entities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 301 | 317
Gross Unrealized Gains | 1 | 0
Gross Unrealized Losses | (1) | (4)
Total securities available for sale, fair value | 301 | 313
Agency Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 1,318 | 1,465
Gross Unrealized Gains | 3 | 0
Gross Unrealized Losses | (6) | (36)
Total securities available for sale, fair value | 1,315 | 1,429
Agency Collateralized Mortgage Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 1,233 | 1,179
Gross Unrealized Gains | 14 | 5
Gross Unrealized Losses | (5) | (23)
Total securities available for sale, fair value | 1,242 | 1,161
Commercial Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 227 | 229
Gross Unrealized Gains | 5 | 0
Gross Unrealized Losses | 0 | (1)
Total securities available for sale, fair value | 232 | 228
States of the U.S. and Political Subdivisions [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 15 | 21
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Total securities available for sale, fair value | 15 | 21
Other Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 2 | 2
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Total securities available for sale, fair value | $ 2 | $ 2

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 + Details
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