NOTES PAYABLE AND LEASE OBLIGATIONS - Summary of Notes Payable (Parenthetical) (Details) ¥ in Billions, $ in Billions	Sep. 30, 2020 USD ($)	Sep. 30, 2020 JPY (¥)	Apr. 30, 2020 USD ($)	Mar. 31, 2020 JPY (¥)	Jan. 31, 2020	Dec. 31, 2019 JPY (¥)
4.00% senior notes paid January 2020
Debt Instrument [Line Items]
Debt instrument, interest rate					4.00%	4.00%
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%				3.625%
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%				3.625%
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	3.25%	3.25%				3.25%
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	2.875%	2.875%				2.875%
3.60% senior notes due April 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	3.60%	3.60%	3.60%
Debt instrument, principal amount | $	$ 1.0		$ 1.0
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	6.90%	6.90%				6.90%
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Debt instrument, interest rate	6.45%	6.45%				6.45%
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%				4.00%
4.750% senior notes due January 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	4.75%	4.75%				4.75%
.300% senior notes due September 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	0.30%	0.30%		0.30%
Debt instrument, principal amount		¥ 12.4		¥ 12.4
.932% senior notes due January 2027
Debt Instrument [Line Items]
Debt instrument, interest rate	0.932%	0.932%				0.932%
Debt instrument, principal amount		¥ 60.0				¥ 60.0
.500% senior noted due December 2029
Debt Instrument [Line Items]
Debt instrument, interest rate	0.50%	0.50%				0.50%
Debt instrument, principal amount		¥ 12.6				¥ 12.6
.550% senior notes due March 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	0.55%	0.55%		0.55%
Debt instrument, principal amount		¥ 13.3		¥ 13.3
1.159% senior notes due October 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	1.159%	1.159%				1.159%
Debt instrument, principal amount		¥ 29.3				¥ 29.3
.843% senior notes due December 2031
Debt Instrument [Line Items]
Debt instrument, interest rate	0.843%	0.843%				0.843%
Debt instrument, principal amount		¥ 9.3				¥ 9.3
.750% senior notes due March 2032
Debt Instrument [Line Items]
Debt instrument, interest rate	0.75%	0.75%		0.75%
Debt instrument, principal amount		¥ 20.7		¥ 20.7
1.488% senior notes due October 2033
Debt Instrument [Line Items]
Debt instrument, interest rate	1.488%	1.488%				1.488%
Debt instrument, principal amount		¥ 15.2				¥ 15.2
.934% senior notes due December 2034
Debt Instrument [Line Items]
Debt instrument, interest rate	0.934%	0.934%				0.934%
Debt instrument, principal amount		¥ 9.8				¥ 9.8
.830% senior notes due March 2035
Debt Instrument [Line Items]
Debt instrument, interest rate	0.83%	0.83%		0.83%
Debt instrument, principal amount		¥ 10.6		¥ 10.6
1.750% senior notes due October 2038
Debt Instrument [Line Items]
Debt instrument, interest rate	1.75%	1.75%				1.75%
Debt instrument, principal amount		¥ 8.9				¥ 8.9
1.122% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	1.122%	1.122%				1.122%
Debt instrument, principal amount		¥ 6.3				¥ 6.3
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Debt instrument, interest rate	2.108%	2.108%				2.108%
Debt instrument, principal amount		¥ 60.0				¥ 60.0
.963% subordinate bond due April 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	0.963%	0.963%				0.963%
Debt instrument, principal amount		¥ 30.0				¥ 30.0
Yen-denominated loan variable interest rate due September 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	0.42%	0.42%				0.32%
Debt instrument, principal amount		¥ 5.0				¥ 5.0
Yen-denominated loan variable interest rate due September 2029
Debt Instrument [Line Items]
Debt instrument, interest rate	0.57%	0.57%				0.47%
Debt instrument, principal amount		¥ 25.0				¥ 25.0