v3.25.2
Condensed Consolidated Statements Of Capitalization - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Stockholders' equity:    
Common stock, $0.50 par value $ 141,951 $ 139,105
Capital in excess of par value 4,420,240 4,199,836
Retained earnings 2,249,401 1,949,492
Treasury stock, at cost (91,390) (89,624)
Total stockholders' equity 6,720,202 6,198,809
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 3,189,533 3,101,096
Total long-term debt 7,801,933 7,559,096
Current portion of long-term debt 132,138 142,807
Long-term debt, excluding current portion 7,669,795 7,416,289
Less: debt issuance costs and unamortized discount on debt 46,801 47,908
Long-term debt, excluding current portion, net of debt issuance costs and unamortized discount on debt 7,622,994 7,368,381
Total capitalization 14,343,196 13,567,190
Notes Ranging From 0.00% To 0.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 2,679 2,637
Notes Ranging From 1.00% To 1.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 20,667 11,732
Notes Ranging From 2.00% To 2.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 205,559 206,297
Notes Ranging From 3.00% To 3.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 1,255,225 1,258,003
Notes Ranging From 4.00% To 4.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 1,237,573 1,239,032
Notes Ranging From 5.00% To 5.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 412,260 312,260
Notes Ranging From 6.00% To 6.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 31,000 31,000
Notes Ranging From 7.00% To 7.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 12,770 27,888
Notes Ranging From 8.00% To 8.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries   447
Notes Ranging From 9.00% To 9.99% [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Long-term debt of subsidiaries 11,800 11,800
Revolving Credit Agreement, Due 2027 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Notes payable to bank under revolving credit agreement, variable rate, due 2027   413,000
Commercial Paper Program [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 567,400  
Notes At 2.40% Due 2031 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 400,000 400,000
Notes At 2.704% Due 2030 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 500,000 500,000
Notes Ranging From 3.01% To 3.59% Due 2029 Through 2050 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 1,125,000 1,125,000
Notes At 4.276%, Due 2049 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 500,000 500,000
Notes At 4.80%, Due 2027 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 500,000 500,000
Notes At 5.30%, Due 2052 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 500,000 500,000
Notes At 5.375%, Due 2034 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable 500,000 500,000
Notes At 5.95%, Due 2033 through 2034 [Member]    
Long-term debt of subsidiaries (substantially collateralized by utility plant):    
Unsecured notes payable $ 20,000 $ 20,000