Long-Term Debt (Schedule of Long-Term Debt Instruments) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2018	Jun. 04, 2018	Mar. 05, 2018
Debt Instrument [Line Items]
Total PSE long-term debt	$ 6,584,372,000
Long Term Debt, Reconciliation, Fair Value Adjustment	(173,865,000)	$ (182,372,000)
Long-term Debt, term loan			$ 210,000,000.0
Long-term Line of Credit, Noncurrent	24,100,000	11,900,000
Unamortized discount on senior notes	(52,000)	(1,897,000)
Long-term Debt, Excluding Current Maturities	5,920,325,000	5,672,491,000
Current maturities of long-term debt	452,412,000	0
$174M Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, term loan	174,000,000	150,000,000	$ 150,000,000.0
$210M Term Loan Due 2022
Debt Instrument [Line Items]
Long-term Debt, term loan	$ 210,000,000	0
Senior Secured Note | 6.500% Senior Secured Note Due 2020
Debt Instrument [Line Items]
Stated interest rate percent	6.50%
Total PSE long-term debt	$ 0	450,000,000
Current maturities of long-term debt	$ 450,000,000.0
Senior Secured Note | 6.000% Senior Secured Note Due 2021
Debt Instrument [Line Items]
Stated interest rate percent	6.00%
Total PSE long-term debt	$ 500,000,000	500,000,000
Senior Secured Note | 5.625% Senior Secured Note Due 2022
Debt Instrument [Line Items]
Stated interest rate percent	5.625%
Total PSE long-term debt	$ 450,000,000	450,000,000
Senior Secured Note | 3.650% Senior Secured Note Due 2025 [Member]
Debt Instrument [Line Items]
Stated interest rate percent	3.65%
Total PSE long-term debt	$ 400,000,000	400,000,000
Subsidiaries [Member]
Debt Instrument [Line Items]
Total PSE long-term debt	4,376,272,000
Unamortized discount on senior notes	(37,718,000)	(31,412,000)
Long-term Debt, Excluding Current Maturities	4,336,142,000	3,894,860,000
Current maturities of long-term debt	$ 2,412,000	0
Subsidiaries [Member] | Senior Notes and First Mortgage Bonds | 5.500% Secured Promissory Note Due 2017
Debt Instrument [Line Items]
Stated interest rate percent	5.50%
Total PSE long-term debt	$ 0	2,412,000
Current maturities of long-term debt	$ 2,400,000
Subsidiaries [Member] | Senior Notes and First Mortgage Bonds | 7.150% Series Due 2025
Debt Instrument [Line Items]
Stated interest rate percent	7.15%
Total PSE long-term debt	$ 15,000,000	15,000,000
Subsidiaries [Member] | Senior Notes and First Mortgage Bonds | 7.200% Series Due 2025
Debt Instrument [Line Items]
Stated interest rate percent	7.20%
Total PSE long-term debt	$ 2,000,000	2,000,000
Subsidiaries [Member] | Pollution Control Bonds | 3.900% Series Due 2031
Debt Instrument [Line Items]
Stated interest rate percent	3.90%
Total PSE long-term debt	$ 138,460,000	138,460,000
Subsidiaries [Member] | Pollution Control Bonds | 4.000% Series Due 2031
Debt Instrument [Line Items]
Stated interest rate percent	4.00%
Total PSE long-term debt	$ 23,400,000	23,400,000
Subsidiaries [Member] | Senior Secured Note | 7.020% Series Due 2027
Debt Instrument [Line Items]
Stated interest rate percent	7.02%
Total PSE long-term debt	$ 300,000,000	300,000,000
Subsidiaries [Member] | Senior Secured Note | 7.000% Series Due 2029
Debt Instrument [Line Items]
Stated interest rate percent	7.00%
Total PSE long-term debt	$ 100,000,000	100,000,000
Subsidiaries [Member] | Senior Secured Note | 5.483% Series Due 2035
Debt Instrument [Line Items]
Stated interest rate percent	5.483%
Total PSE long-term debt	$ 250,000,000	250,000,000
Subsidiaries [Member] | Senior Secured Note | 6.724% Series Due 2036
Debt Instrument [Line Items]
Stated interest rate percent	6.724%
Total PSE long-term debt	$ 250,000,000	250,000,000
Subsidiaries [Member] | Senior Secured Note | 6.274% Series Due 2037
Debt Instrument [Line Items]
Stated interest rate percent					6.274%
Total PSE long-term debt	$ 300,000,000	300,000,000
Subsidiaries [Member] | Senior Secured Note | 5.757% Series Due 2039
Debt Instrument [Line Items]
Stated interest rate percent	5.757%
Total PSE long-term debt	$ 350,000,000	350,000,000
Subsidiaries [Member] | Senior Secured Note | 5.795% Series Due 2040
Debt Instrument [Line Items]
Stated interest rate percent	5.795%
Total PSE long-term debt	$ 325,000,000	325,000,000
Subsidiaries [Member] | Senior Secured Note | 5.764% Series Due 2040
Debt Instrument [Line Items]
Stated interest rate percent	5.764%
Total PSE long-term debt	$ 250,000,000	250,000,000
Subsidiaries [Member] | Senior Secured Note | 4.434% Series Due 2041
Debt Instrument [Line Items]
Stated interest rate percent	4.434%
Total PSE long-term debt	$ 250,000,000	250,000,000
Subsidiaries [Member] | Senior Secured Note | 5.638% Series Due 2041
Debt Instrument [Line Items]
Stated interest rate percent	5.638%
Total PSE long-term debt	$ 300,000,000	300,000,000
Subsidiaries [Member] | Senior Secured Note | 4.300% Series Due 2045
Debt Instrument [Line Items]
Stated interest rate percent	4.30%
Total PSE long-term debt	$ 425,000,000	425,000,000
Subsidiaries [Member] | Senior Secured Note | 4.223% Series Due 2048
Debt Instrument [Line Items]
Stated interest rate percent	4.223%			4.223%
Total PSE long-term debt	$ 600,000,000	600,000,000		$ 600,000,000.0
Subsidiaries [Member] | Senior Secured Note | 3.250% Senior Secured Note Due 2049 [Member]
Debt Instrument [Line Items]
Stated interest rate percent	3.25%
Total PSE long-term debt	$ 450,000,000.0	0
Subsidiaries [Member] | Senior Secured Note | 4.700% Series Due 2051
Debt Instrument [Line Items]
Stated interest rate percent	4.70%
Total PSE long-term debt	$ 45,000,000	$ 45,000,000