v3.26.1
Leases - Supplemental balance sheet information related to leases (Details)
$ in Thousands
Jun. 30, 2026
USD ($)
Jun. 26, 2026
USD ($)
MW
Dec. 31, 2025
USD ($)
Lessor, Lease, Description [Line Items]      
Total operating lease right-of-use assets $ 433,194   $ 460,990
Operating lease liabilities 106,631   104,240
Operating lease liabilities 334,762   365,359
Operating Lease, Liability 441,393   469,599
Total finance lease assets 154,717   159,476
Finance Lease, Liability, Current 5,623   5,586
Finance lease liabilities 164,681   167,426
Total finance lease liabilities 170,304   173,012
Subsidiaries      
Lessor, Lease, Description [Line Items]      
Total operating lease right-of-use assets 433,194   460,990
Operating lease liabilities 106,631   104,240
Operating lease liabilities 334,762   365,359
Finance lease liabilities 164,681   167,426
Subsidiaries | Grays Harbor Tolling      
Lessor, Lease, Description [Line Items]      
Total operating lease right-of-use assets   $ 122,600  
Operating Lease, Liability   $ 122,100  
Nameplate Capacity | MW   650,000,000  
Common Plant      
Lessor, Lease, Description [Line Items]      
Total finance lease assets 120,783   124,343
Natural Gas Processing Plant      
Lessor, Lease, Description [Line Items]      
Total finance lease assets 119   209
Electric Plant      
Lessor, Lease, Description [Line Items]      
Total finance lease assets 33,815   34,924
Other Current Liabilities      
Lessor, Lease, Description [Line Items]      
Operating lease liabilities 22,570   21,830
Other Noncurrent Liabilities      
Lessor, Lease, Description [Line Items]      
Operating lease liabilities 225,950   230,686
Purchase Power Contract      
Lessor, Lease, Description [Line Items]      
Total operating lease right-of-use assets 192,977   216,935
Operating lease liabilities 84,061   82,410
Operating lease liabilities 108,812   134,673
Other      
Lessor, Lease, Description [Line Items]      
Total operating lease right-of-use assets $ 240,217   $ 244,055