NOTES PAYABLE AND LEASE OBLIGATIONS - Summary of Notes Payable (Parenthetical) (Details) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Jan. 31, 2020	Dec. 31, 2019
4.00% senior notes paid January 2020
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	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% senior notes due November 2024
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%		3.625%
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	3.25%		3.25%
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	2.875%		2.875%
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	6.90%		6.90%
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Debt instrument, interest rate	6.45%		6.45%
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%		4.00%
4.750% senior notes due January 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	4.75%		4.75%
.300% senior notes due September 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	0.30%
Debt instrument, principal amount	¥ 12.4
.932% senior notes due January 2027
Debt Instrument [Line Items]
Debt instrument, interest rate	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%
Debt instrument, principal amount	¥ 12.6		¥ 12.6
.550% senior notes due March 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	0.55%
Debt instrument, principal amount	¥ 13.3
1.159% senior notes due October 2030
Debt Instrument [Line Items]
Debt instrument, interest rate	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%
Debt instrument, principal amount	¥ 9.3		¥ 9.3
.750% senior notes due March 2032
Debt Instrument [Line Items]
Debt instrument, interest rate	0.75%
Debt instrument, principal amount	¥ 20.7
1.488% senior notes due October 2033
Debt Instrument [Line Items]
Debt instrument, interest rate	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%
Debt instrument, principal amount	¥ 9.8		¥ 9.8
.830% senior notes due March 2035
Debt Instrument [Line Items]
Debt instrument, interest rate	0.83%
Debt instrument, principal amount	¥ 10.6
1.750% senior notes due October 2038
Debt Instrument [Line Items]
Debt instrument, interest rate	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%
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%
Debt instrument, principal amount	¥ 60.0		¥ 60.0
.936% subordinate bond due April 2049
Debt Instrument [Line Items]
Debt instrument, interest rate	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%
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%
Debt instrument, principal amount	¥ 25.0		¥ 25.0