CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenues	$ 8,448,201	$ 7,751,952	$ 7,639,129
Operating Expenses:
Purchased Power, Fuel and Transmission	3,138,969	2,535,271	2,500,828
Operations and Maintenance	1,335,213	1,307,052	1,342,134
Depreciation	819,930	773,802	715,466
Amortization of Regulatory Assets/(Liabilities), Net	252,026	89,986	71,696
Energy Efficiency Programs	472,380	480,835	533,659
Taxes Other Than Income Taxes	729,753	676,757	634,072
Total Operating Expenses	6,748,271	5,863,703	5,797,855
Operating Income	1,699,930	1,888,249	1,841,274
Interest Expense	498,805	421,755	400,961
Other Income, Net	128,366	107,913	64,505
Income Before Income Tax Benefit	1,329,491	1,574,407	1,504,818
Income Tax Expense	288,972	578,892	554,997
Net Income	1,040,519	995,515	949,821
Net Income Attributable to Noncontrolling Interests	7,519	7,519	7,519
Net Income/(Loss) Attributable to Common Shareholders	$ 1,033,000	$ 987,996	$ 942,302
Basic Earnings Per Common Share (in dollars per share)	$ 3.25	$ 3.11	$ 2.97
Diluted Earnings Per Common Share (in dollars per share)	$ 3.25	$ 3.11	$ 2.96
Weighted Average Common Shares Outstanding:
Basic (in shares)	317,370,369	317,411,097	317,650,180
Diluted (in shares)	317,993,934	318,031,580	318,454,239
The Connecticut Light And Power Company
Operating Revenues	$ 3,096,174	$ 2,887,359	$ 2,805,955
Operating Expenses:
Purchased Power, Fuel and Transmission	1,095,187	930,780	919,723
Operations and Maintenance	506,448	502,107	490,810
Depreciation	278,557	249,352	230,489
Amortization of Regulatory Assets/(Liabilities), Net	129,021	83,166	38,765
Energy Efficiency Programs	93,977	114,713	154,015
Taxes Other Than Income Taxes	357,147	323,887	299,719
Total Operating Expenses	2,460,337	2,204,005	2,133,521
Operating Income	635,837	683,354	672,434
Interest Expense	151,727	142,973	144,110
Other Income, Net	22,663	22,991	14,238
Income Before Income Tax Benefit	506,773	563,372	542,562
Income Tax Expense	129,056	186,646	208,308
Net Income	377,717	376,726	334,254
NSTAR Electric Company
Operating Revenues	3,112,926	2,980,629	3,041,588
Operating Expenses:
Purchased Power, Fuel and Transmission	1,257,073	1,025,414	1,084,324
Operations and Maintenance	462,100	482,924	500,315
Depreciation	276,372	274,008	259,262
Amortization of Regulatory Assets/(Liabilities), Net	46,654	33,831	34,332
Energy Efficiency Programs	292,288	294,053	321,787
Taxes Other Than Income Taxes	194,316	181,959	177,837
Total Operating Expenses	2,528,803	2,292,189	2,377,857
Operating Income	584,123	688,440	663,731
Interest Expense	105,193	105,729	108,428
Other Income, Net	53,066	34,100	21,263
Income Before Income Tax Benefit	531,996	616,811	576,566
Income Tax Expense	148,906	242,085	225,789
Net Income	383,090	374,726	350,777
Public Service Company Of New Hampshire
Operating Revenues	1,047,619	981,624	959,482
Operating Expenses:
Purchased Power, Fuel and Transmission	370,246	237,478	210,786
Operations and Maintenance	210,541	263,110	267,013
Depreciation	92,055	128,192	116,519
Amortization of Regulatory Assets/(Liabilities), Net	80,978	(16,577)	11,170
Energy Efficiency Programs	20,105	13,788	14,204
Taxes Other Than Income Taxes	77,280	89,760	82,964
Total Operating Expenses	851,205	715,751	702,656
Operating Income	196,414	265,873	256,826
Interest Expense	60,634	51,007	50,040
Other Income, Net	27,672	9,805	7,563
Income Before Income Tax Benefit	163,452	224,671	214,349
Income Tax Expense	47,576	88,675	82,364
Net Income	$ 115,876	$ 135,996	$ 131,985