XML 61 R50.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value Measurements (Carrying Values And Fair Values Of Financial Instruments Not Measured At Fair Value) (Detail) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value $ 14,122 $ 14,474
Held-to-maturity Securities 14,253 14,335
Repurchase agreements 1,412 1,408
Short-term debt 1,669 1,013
Long-term debt 12,786 11,556
Trust preferred securities 308 308
Total liabilities 117,494 115,850
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 977 857
Repurchase agreements 0 0
Short-term Debt, Fair Value 0 0
Long-term Debt, Fair Value 0 0
Trust preferred securities 0 0
Total liabilities 0 0
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 13,112 13,582
Repurchase agreements 1,412 1,408
Short-term Debt, Fair Value 1,704 1,013
Long-term Debt, Fair Value 13,023 12,332
Trust preferred securities 466 468
Total liabilities 16,605 15,221
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 33 35
Repurchase agreements 0 0
Short-term Debt, Fair Value 0 0
Long-term Debt, Fair Value 0 0
Trust preferred securities 0 0
Total liabilities 0 0
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 977 857
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 55 58
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Foreign [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Foreign [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 1,751 1,757
Foreign [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Corporate [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Corporate [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 2,964 3,184
Corporate [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 33 35
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 2,647 2,742
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 5,695 5,841
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 0 0
Estimate of Fair Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 14,122 14,474
Repurchase agreements 1,412 1,408
Short-term Debt, Fair Value 1,704 1,013
Long-term Debt, Fair Value 13,023 12,332
Trust preferred securities 466 468
Total liabilities 16,605 15,221
Estimate of Fair Value Measurement [Member] | U.S. Treasury And Agency [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 1,032 915
Estimate of Fair Value Measurement [Member] | Foreign [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 1,751 1,757
Estimate of Fair Value Measurement [Member] | Corporate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 2,997 3,219
Estimate of Fair Value Measurement [Member] | Collateralized Mortgage Backed Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 2,647 2,742
Estimate of Fair Value Measurement [Member] | States, Municipalities, And Political Subdivisions [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities, Fair Value 5,695 5,841
Reported Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities 14,253 14,335
Repurchase agreements 1,412 1,408
Short-term debt 1,669 1,013
Long-term debt 12,786 11,556
Trust preferred securities 308 308
Total liabilities 16,175 14,285
Reported Value Measurement [Member] | U.S. Treasury And Agency [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities 1,037 908
Reported Value Measurement [Member] | Foreign [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities 1,754 1,738
Reported Value Measurement [Member] | Corporate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities 3,026 3,159
Reported Value Measurement [Member] | Collateralized Mortgage Backed Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities 2,681 2,724
Reported Value Measurement [Member] | States, Municipalities, And Political Subdivisions [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Held-to-maturity Securities $ 5,755 $ 5,806