LEASES - Future Minimum Lease Payments under Long-Term Leases (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Operating Leases
2026	$ 11.5
2027	7.1
2028	6.8
2029	4.7
2030	4.3
Thereafter	22.0
Future lease payments	56.4
Less amount representing interest	9.0
Present value of future minimum lease payments	47.4	$ 56.1
Finance Leases
2026	27.9
2027	8.2
2028	7.5
2029	7.3
2030	7.3
Thereafter	43.1
Future lease payments	101.3
Less amount representing interest	19.6
Present value of future minimum lease payments	81.7	67.7
CL&P
Operating Leases
2026	2.6
2027	2.0
2028	1.9
2029	0.1
2030	0.0
Thereafter	0.1
Future lease payments	6.7
Less amount representing interest	0.6
Present value of future minimum lease payments	6.1	7.7
Finance Leases
2026	2.4
2027	2.5
2028	2.6
2029	2.6
2030	2.6
Thereafter	6.2
Future lease payments	18.9
Less amount representing interest	3.3
Present value of future minimum lease payments	15.6	17.1
NSTAR Electric
Operating Leases
2026	5.0
2027	2.8
2028	2.8
2029	2.5
2030	2.5
Thereafter	19.6
Future lease payments	35.2
Less amount representing interest	8.0
Present value of future minimum lease payments	27.2	29.4
Finance Leases
2026	0.7
2027	0.7
2028	0.7
2029	0.7
2030	0.7
Thereafter	9.6
Future lease payments	13.1
Less amount representing interest	8.2
Present value of future minimum lease payments	4.9	4.9
PSNH
Operating Leases
2026	1.5
2027	0.1
2028	0.0
2029	0.0
2030	0.0
Thereafter	0.1
Future lease payments	1.7
Less amount representing interest	0.2
Present value of future minimum lease payments	1.5	3.3
Finance Leases
2026	0.2
2027	0.2
2028	0.2
2029	0.0
2030	0.0
Thereafter	0.0
Future lease payments	0.6
Less amount representing interest	0.1
Present value of future minimum lease payments	$ 0.5	$ 0.0