LONG-TERM DEBT (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Maturities of Long-term Debt

Details of long-term debt outstanding are as follows:

CL&P (Millions of Dollars)	As of December 31,
	2016			2015
First Mortgage Bonds:
7.875% 1994 Series D due 2024	$	139.8		$	139.8
5.750% 2004 Series B due 2034	130.0			130.0
5.625% 2005 Series B due 2035	100.0			100.0
6.350% 2006 Series A due 2036	250.0			250.0
5.375% 2007 Series A due 2017	150.0			150.0
5.750% 2007 Series B due 2037	150.0			150.0
5.750% 2007 Series C due 2017	100.0			100.0
6.375% 2007 Series D due 2037	100.0			100.0
5.650% 2008 Series A due 2018	300.0			300.0
5.500% 2009 Series A due 2019	250.0			250.0
2.500% 2013 Series A due 2023	400.0			400.0
4.300% 2014 Series A due 2044	250.0			250.0
4.150% 2015 Series A due 2045	350.0			350.0
Total First Mortgage Bonds	2,669.8			2,669.8
Pollution Control Revenue Bonds:
4.375% Fixed Rate Tax Exempt due 2028	120.5			120.5
Less Amounts due Within One Year	(250.0		)	—
Unamortized Premiums and Discounts, Net	(10.0		)	(10.7		)
Unamortized Debt Issuance Costs	(14.3		)	(15.9		)
CL&P Long-Term Debt	$	2,516.0		$	2,763.7

NSTAR Electric (Millions of Dollars)	As of December 31,
	2016			2015
Debentures:
5.750% due 2036	$	200.0		$	200.0
5.625% due 2017	400.0			400.0
5.500% due 2040	300.0			300.0
2.375% due 2022	400.0			400.0
Variable Rate due 2016 (0.6036% as of December 31, 2015)	—			200.0
4.400% due 2044	300.0			300.0
3.250% due 2025	250.0			250.0
2.700% due 2026	250.0			—
Total Debentures	2,100.0			2,050.0
Less Amounts due Within One Year	(400.0		)	(200.0		)
Unamortized Premiums and Discounts, Net	(9.1		)	(8.5		)
Unamortized Debt Issuance Costs	(12.8		)	(11.7		)
NSTAR Electric Long-Term Debt	$	1,678.1		$	1,829.8

PSNH (Millions of Dollars)	As of December 31,
	2016			2015
First Mortgage Bonds:
5.600% Series M due 2035	$	50.0		$	50.0
6.150% Series N due 2017	70.0			70.0
6.000% Series O due 2018	110.0			110.0
4.500% Series P due 2019	150.0			150.0
4.050% Series Q due 2021	122.0			122.0
3.200% Series R due 2021	160.0			160.0
3.500% Series S due 2023	325.0			325.0
Total First Mortgage Bonds	987.0			987.0
Pollution Control Revenue Bonds:
Adjustable Rate Tax Exempt Series A due 2021      (1.138% and 0.193% as of December 31, 2016 and 2015, respectively)	89.3			89.3
Less Amounts due Within One Year	(70.0		)	—
Unamortized Premiums and Discounts, Net	0.1			0.1
Unamortized Debt Issuance Costs	(4.4		)	(5.4		)
PSNH Long-Term Debt	$	1,002.0		$	1,071.0

WMECO (Millions of Dollars)	As of December 31,
	2016			2015
Notes:
5.900% Senior Notes Series B due 2034	$	50.0		$	50.0
6.700% Senior Notes Series D due 2037	40.0			40.0
5.100% Senior Notes Series E due 2020	95.0			95.0
3.500% Senior Notes Series F due 2021	250.0			250.0
3.880% Senior Notes Series G due 2023	80.0			80.0
2.750% Senior Notes Series H due 2026	50.0			—
Total Notes	565.0			515.0
Unamortized Premiums and Discounts, Net	4.2			5.2
Unamortized Debt Issuance Costs	(2.7		)	(2.9		)
WMECO Long-Term Debt	$	566.5		$	517.3

OTHER (Millions of Dollars)	As of December 31,
	2016			2015
Yankee Gas - First Mortgage Bonds:
8.480% Series B due 2022	$	20.0		$	20.0
5.260% Series H due 2019	50.0			50.0
5.350% Series I due 2035	50.0			50.0
6.900% Series J due 2018	100.0			100.0
4.870% Series K due 2020	50.0			50.0
4.820% Series L due 2044	100.0			100.0
3.350% Series M due 2025	75.0			75.0
Total First Mortgage Bonds	445.0			445.0
Unamortized Premium	0.4			0.4
Unamortized Debt Issuance Costs	(1.5		)	(1.7		)
Yankee Gas Long-Term Debt	443.9			443.7
NSTAR Gas - First Mortgage Bonds:
9.950% Series J due 2020	25.0			25.0
7.110% Series K due 2033	35.0			35.0
7.040% Series M due 2017	25.0			25.0
4.460% Series N due 2020	125.0			125.0
4.350% Series O due 2045	100.0			100.0
Total First Mortgage Bonds	310.0			310.0
Less Amounts due Within One Year	(25.0		)	—
Unamortized Debt Issuance Costs	(0.7		)	(0.8		)
NSTAR Gas Long-Term Debt	284.3			309.2
Eversource Parent - Notes and Debentures:
4.500% Debentures due 2019	350.0			350.0
1.450% Senior Notes Series E due 2018	300.0			300.0
2.800% Senior Notes Series F due 2023	450.0			450.0
1.600% Senior Notes Series G due 2018	150.0			150.0
3.150% Senior Notes Series H due 2025	300.0			300.0
2.500% Senior Notes Series I due 2021	250.0			—
3.350% Senior Notes Series J due 2026	250.0			—
Total Eversource Parent Notes and Debentures	2,050.0			1,550.0
Pre-1983 Spent Nuclear Fuel Obligation (CYAPC)	180.0			179.5
Fair Value Adjustment (1)	144.6			173.5
Less Fair Value Adjustment - Current Portion (1)	(28.9		)	(28.9		)
Unamortized Premiums and Discounts, Net	(2.2		)	(1.3		)
Unamortized Debt Issuance Costs	(4.9		)	(1.9		)
Total Other Long-Term Debt	$	3,066.8		$	2,623.8
Total Eversource Long-Term Debt	$	8,829.4		$	8,805.6

⁽¹⁾   The fair value adjustment amount is the purchase price adjustment, net of amortization, required to record the NSTAR long-term debt at fair value on the date of the 2012 merger.

Schedule of Long-term Debt Instruments

Long-term debt maturities on debt outstanding for the years 2017 through 2021 and thereafter are shown below. These amounts exclude the CYAPC pre-1983 spent nuclear fuel obligation, net unamortized premiums, discounts and debt issuance costs, and other fair value adjustments as of December 31, 2016:

(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		WMECO
2017	$	745.0	$	250.0	$	400.0	$	70.0	$	—
2018	960.0		300.0		—		110.0		—
2019	800.0		250.0		—		150.0		—
2020	295.0		—		—		—		95.0
2021	871.3		—		—		371.3		250.0
Thereafter	5,665.3		1,990.3		1,700.0		375.0		220.0
Total	$	9,336.6	$	2,790.3	$	2,100.0	$	1,076.3	$	565.0