CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities:
Net Income	$ 1,040,519	$ 995,515	$ 949,821
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities
Depreciation	819,930	773,802	715,466
Deferred Income Taxes	174,812	491,630	466,463
Bad Debt Expense	61,337	44,453	69,466
Pension, SERP and PBOP Expense, Net	5,498	22,454	39,912
Pension and PBOP Contributions	(194,947)	(242,800)	(158,741)
Regulatory Over/(Under) Recoveries, Net	34,920	(47,935)	13,340
Amortization of Regulatory Assets, Net	(252,026)	(89,986)	(71,696)
(Payments)/Refunds Related to Spent Nuclear Fuel, Net	(145,000)	0	59,804
Other	(111,225)	(204,421)	(118,195)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(141,433)	(117,155)	(142,699)
Fuel, Materials, Supplies and Inventory	(831)	(9,223)	7,755
Taxes Receivable/Accrued, Net	(67,770)	52,284	234,543
Accounts Payable	(22,084)	56,067	(14,126)
Other Current Assets and Liabilities, Net	78,226	91,545	13,737
Net Cash Flows Provided by Operating Activities	1,783,978	1,996,202	2,208,242
Investing Activities:
Investments in Property, Plant and Equipment	(2,523,371)	(2,348,105)	(1,976,867)
Proceeds from Sales of Marketable Securities	900,749	832,903	659,338
Proceeds from Sales of Marketable Securities Used to Pay Spent Nuclear Fuel Obligation	145,000	0	0
Purchases of Marketable Securities	(908,387)	(810,507)	(681,272)
Acquisition of Aquarion	0	(877,652)	0
Payments to Acquire Investments	(205,150)	(32,634)	(188,958)
Proceeds from the Sale of PSNH Generation Assets	193,924	0	0
Other Investing Activities	6,754	5,479	36,211
Net Cash Flows Used in Investing Activities	(2,390,481)	(3,230,516)	(2,151,548)
Financing Activities:
Cash Dividends on Common Shares	(640,110)	(602,083)	(564,486)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
Increase/(Decrease) in Short-Term Debt	(379,310)	72,810	(12,453)
Issuance of Rate Reduction Bonds	635,663	0	0
Issuance of Long-Term Debt	2,200,000	2,500,000	800,000
Retirements of Long-Term Debt	(1,050,330)	(745,000)	(200,000)
Other Financing Activities	(28,457)	(4,754)	(33,482)
Net Cash Flows Provided by/(Used in) Financing Activities	729,937	1,213,454	(17,940)
Net Increase/(Decrease) in Cash, Cash Equivalents and Restricted Cash	123,434	(20,860)	38,754
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	85,890	106,750	67,996
Cash and Restricted Cash - End of Year	209,324	85,890	106,750
The Connecticut Light And Power Company
Operating Activities:
Net Income	377,717	376,726	334,254
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities
Depreciation	278,557	249,352	230,489
Deferred Income Taxes	54,859	119,295	168,919
Bad Debt Expense	15,831	5,312	17,572
Pension, SERP and PBOP Expense, Net	8,943	9,909	7,328
Pension and PBOP Contributions	(41,150)	(2,500)	(380)
Regulatory Over/(Under) Recoveries, Net	(53,372)	(8,017)	(68,730)
Amortization of Regulatory Assets, Net	(129,021)	(83,166)	(38,765)
Other	(69,786)	(42,973)	(36,245)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(67,334)	(47,768)	3,229
Fuel, Materials, Supplies and Inventory	3,909	3,612	(8,926)
Taxes Receivable/Accrued, Net	8,954	(9,688)	123,692
Accounts Payable	(76,924)	48,032	3,252
Other Current Assets and Liabilities, Net	18,846	21,860	(1,065)
Net Cash Flows Provided by Operating Activities	588,071	806,318	812,154
Investing Activities:
Investments in Property, Plant and Equipment	(864,136)	(824,383)	(611,984)
Proceeds from the Sale of PSNH Generation Assets	0	0	9,047
Other Investing Activities	209	236	296
Net Cash Flows Used in Investing Activities	(863,927)	(824,147)	(602,641)
Financing Activities:
Cash Dividends on Common Shares	(60,000)	(254,800)	(199,599)
(Decrease)/Increase in Notes Payable to Eversource Parent	(69,500)	(10,600)	(197,300)
Cash Dividends on Preferred Stock	(5,559)	(5,559)	(5,559)
Issuance of Long-Term Debt	500,000	525,000	0
Retirements of Long-Term Debt	(300,000)	(250,000)	0
Capital Contributions from Eversource Parent	300,000	0	200,000
Other Financing Activities	(7,091)	15,004	(857)
Net Cash Flows Provided by/(Used in) Financing Activities	357,850	19,045	(203,315)
Net Increase/(Decrease) in Cash, Cash Equivalents and Restricted Cash	81,994	1,216	6,198
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	9,619	8,403	2,205
Cash and Restricted Cash - End of Year	91,613	9,619	8,403
NSTAR Electric Company
Operating Activities:
Net Income	383,090	374,726	350,777
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities
Depreciation	276,372	274,008	259,262
Deferred Income Taxes	41,438	110,499	101,698
Bad Debt Expense	22,279	21,252	31,728
Pension, SERP and PBOP Expense, Net	(21,521)	(9,509)	(771)
Pension and PBOP Contributions	(61,751)	(90,721)	(37,305)
Regulatory Over/(Under) Recoveries, Net	149,647	(20,009)	118,385
Amortization of Regulatory Assets, Net	(46,654)	(33,831)	(34,332)
Other	(65,523)	(24,872)	(50,831)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(26,403)	(50,896)	(70,302)
Fuel, Materials, Supplies and Inventory	(18,685)	(24,610)	10,571
Taxes Receivable/Accrued, Net	(33,900)	39,205	60,774
Accounts Payable	37,140	(20,421)	18,000
Other Current Assets and Liabilities, Net	51,674	26,849	(14,227)
Net Cash Flows Provided by Operating Activities	780,511	639,332	812,091
Investing Activities:
Investments in Property, Plant and Equipment	(725,766)	(719,623)	(664,932)
Other Investing Activities	58	(3,552)	53
Net Cash Flows Used in Investing Activities	(725,708)	(723,175)	(664,879)
Financing Activities:
Cash Dividends on Common Shares	(228,000)	(272,000)	(316,300)
Cash Dividends on Preferred Stock	(1,960)	(1,960)	(1,960)
Increase/(Decrease) in Short-Term Debt	44,500	56,500	(28,400)
Issuance of Long-Term Debt	0	700,000	300,000
Retirements of Long-Term Debt	0	(400,000)	(200,000)
Capital Contributions from Eversource Parent	130,500	2,300	103,000
Other Financing Activities	108	(1,796)	(866)
Net Cash Flows Provided by/(Used in) Financing Activities	(54,852)	83,044	(144,526)
Net Increase/(Decrease) in Cash, Cash Equivalents and Restricted Cash	(49)	(799)	2,686
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	14,708	15,507	12,821
Cash and Restricted Cash - End of Year	14,659	14,708	15,507
Public Service Company Of New Hampshire
Operating Activities:
Net Income	115,876	135,996	131,985
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities
Depreciation	92,055	128,192	116,519
Deferred Income Taxes	35,924	63,883	87,345
Bad Debt Expense	6,383	6,704	7,288
Pension, SERP and PBOP Expense, Net	754	1,368	875
Pension and PBOP Contributions	0	(800)	(17,078)
Regulatory Over/(Under) Recoveries, Net	(27,264)	(30,788)	(4,491)
Amortization of Regulatory Assets, Net	(80,978)	16,577	(11,170)
Other	(15,363)	(16,813)	3,108
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(19,307)	(22,055)	(18,822)
Fuel, Materials, Supplies and Inventory	16,928	5,519	(5,485)
Taxes Receivable/Accrued, Net	(19,970)	339	32,303
Accounts Payable	(56,712)	29,453	11,353
Other Current Assets and Liabilities, Net	3,028	16,463	4,654
Net Cash Flows Provided by Operating Activities	213,310	300,884	360,724
Investing Activities:
Investments in Property, Plant and Equipment	(277,345)	(312,720)	(305,430)
Proceeds from the Sale of PSNH Generation Assets	193,924	0	0
Proceeds from the Sale of Property	4,782	0	0
Other Investing Activities	437	199	326
Net Cash Flows Used in Investing Activities	(78,202)	(312,521)	(305,104)
Financing Activities:
Cash Dividends on Common Shares	(150,000)	(23,900)	(77,600)
(Decrease)/Increase in Notes Payable to Eversource Parent	(205,900)	102,000	(70,400)
Issuance of Rate Reduction Bonds	635,663	0	0
Return of Capital	(530,000)	0	0
Retirements of Long-Term Debt	(199,250)	(70,000)	0
Capital Contributions from Eversource Parent	365,000	0	94,500
Other Financing Activities	(89)	(225)	(255)
Net Cash Flows Provided by/(Used in) Financing Activities	(84,576)	7,875	(53,755)
Net Increase/(Decrease) in Cash, Cash Equivalents and Restricted Cash	50,532	(3,762)	1,865
Cash, Cash Equivalents and Restricted Cash - Beginning of Year	2,191	5,953	4,088
Cash and Restricted Cash - End of Year	$ 52,723	$ 2,191	$ 5,953