Long-Term Debt Debt Maturity Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 1,292,586	$ 435,000
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	22,343
Long-term Debt, Maturities, Repayments of Principal in Year Two	76,943
Long-term Debt, Maturities, Repayments of Principal in Year Three	39,388
Long-term Debt, Maturities, Repayments of Principal in Year Four	4,583
Long-term Debt, Maturities, Repayments of Principal in Year Five	49,256
Long-term Debt, Maturities, Repayments of Principal after Year Five	1,100,073
Maine Water Company [Member]
Debt Instrument [Line Items]
Long-term debt	38,032	0
Maine Water Company [Member] \| Public Utility, Bonds [Member] \| State Revolving Fund Loans [Member]
Debt Instrument [Line Items]
Long-term debt	$ 16,032	$ 0
Maine Water Company [Member] \| Public Utility, Bonds [Member] \| State Revolving Fund Loans [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Stated interest rates	0.00%
Maine Water Company [Member] \| Public Utility, Bonds [Member] \| State Revolving Fund Loans [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Stated interest rates	2.58%

Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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