Long-Term Debt (Schedule of Long-Term Debt Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2018	Jun. 04, 2018	Mar. 28, 2018	Mar. 05, 2018	Jun. 15, 2017
Debt Instrument [Line Items]
Current borrowing capacity of line of credit	$ 200,000
Proceeds from long-term debt and bonds issued	804,050	$ 90,120	$ 12,481
Total PSE long-term debt	5,888,172
Long Term Debt, Reconciliation, Fair Value Adjustment	(182,372)	(190,895)
Long-term Debt, term loan	150,000	0		$ 150,000
Long-term Line of Credit, Noncurrent	11,900	102,600
Unamortized discount on senior notes	(1,897)	(3,687)
Net PSE long-term debt	$ 5,672,491	5,457,929
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	$ 450,000	450,000
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	500,000
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	450,000
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	400,000
Subsidiaries [Member]
Debt Instrument [Line Items]
Proceeds from long-term debt and bonds issued	594,750	0	$ 0
Total PSE long-term debt	3,926,272
Unamortized discount on senior notes	(31,412)	(26,361)
Net PSE long-term debt	$ 3,894,860	3,749,911
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	$ 2,412	2,412
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	15,000
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	2,000
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	138,460
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	23,400
Subsidiaries [Member] | Junior Subordinated Debt | 6.974% Series Due 2067
Debt Instrument [Line Items]
Stated interest rate percent						6.974%
Total PSE long-term debt	$ 0						$ 250,000
Subsidiaries [Member] | Senior Secured Note | 6.740% Series Due 2018
Debt Instrument [Line Items]
Stated interest rate percent	6.74%							6.74%
Total PSE long-term debt	$ 0	200,000			$ 200,000			$ 200,000
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	300,000
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	100,000
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	250,000
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	250,000
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	300,000
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	350,000
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	325,000
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	250,000
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	250,000
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	300,000
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	425,000
Subsidiaries [Member] | Senior Secured Note | 4.223% Series Due 2048 [Members] [Domain]
Debt Instrument [Line Items]
Stated interest rate percent	4.223%
Total PSE long-term debt	$ 600,000	0			$ 600,000
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	$ 45,000