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DERIVATIVE INSTRUMENTS - Summary of Characteristics of Interest Rate Swaps (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Interest Rate Swaps |  |
Derivative [Line Items] |  |
Current notional | $ 74,146,350,000 | $ 70,465,700,000
Weighted average pay rate | 1.84% | 2.17%
Weighted average receive rate | 1.89% | 2.68%
Weighted average underlying years to maturity | 4 years 2 months 23 days | 4 years 3 months 3 days
Derivative, nonmonetary notional amount, percentage | 0.75 |
Interest Rate Swaps | 0 - 3 years |  |
Derivative [Line Items] |  |
Current notional | $ 38,942,400,000 | $ 31,900,200,000
Weighted average pay rate | 1.60% | 1.84%
Weighted average receive rate | 1.84% | 2.73%
Weighted average underlying years to maturity | 1 year 3 months 14 days | 1 year 2 months 15 days
Derivative instruments, minimum maturity period | 0 years | 0 years
Derivative Instruments maximum maturity period | 3 years | 3 years
Interest Rate Swaps | 3 - 6 years |  |
Derivative [Line Items] |  |
Current notional | $ 16,097,450,000 | $ 16,603,200,000
Weighted average pay rate | 1.77% | 2.29%
Weighted average receive rate | 1.87% | 2.70%
Weighted average underlying years to maturity | 4 years 3 months 18 days | 4 years 3 months 18 days
Derivative instruments, minimum maturity period | 3 years | 3 years
Derivative Instruments maximum maturity period | 6 years | 6 years
Interest Rate Swaps | 6 - 10 years |  |
Derivative [Line Items] |  |
Current notional | $ 16,176,500,000 | $ 18,060,900,000
Weighted average pay rate | 2.20% | 2.57%
Weighted average receive rate | 2.02% | 2.56%
Weighted average underlying years to maturity | 9 years | 8 years 7 months 13 days
Derivative instruments, minimum maturity period | 6 years | 6 years
Derivative Instruments maximum maturity period | 10 years | 10 years
Interest Rate Swaps | Greater than 10 years |  |
Derivative [Line Items] |  |
Current notional | $ 2,930,000,000 | $ 3,901,400,000
Weighted average pay rate | 3.76% | 3.63%
Weighted average receive rate | 1.86% | 2.59%
Weighted average underlying years to maturity | 17 years 10 months 17 days | 17 years 3 months 29 days
Derivative instruments, minimum maturity period | 10 years | 10 years
Forward Starting Pay Fixed Swaps |  |
Derivative [Line Items] |  |
Current notional |  | $ 0
Overnight Index Swap |  |
Derivative [Line Items] |  |
Derivative, nonmonetary notional amount, percentage | 0.25 |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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