v3.26.1
Debt (Narrative) (Details) - USD ($)
$ in Thousands
Apr. 01, 2026
Mar. 31, 2026
Dec. 31, 2025
Debt Instrument [Line Items]      
Long-term Debt   $ 3,904,193 $ 3,903,377
Maximum borrowing capacity   500,000  
Finance Lease, Liability, Current   109 154
Finance Lease, Liability, Noncurrent   107,048 107,079
Obligations      
Debt Instrument [Line Items]      
Finance Lease, Liability, Current   100 200
Finance Lease, Liability, Noncurrent   107,000 107,100
Tax Exempt Refund Revenue Bonds Par Value      
Debt Instrument [Line Items]      
Other Long-Term Debt, Current $ 30,000    
Tax Exempt Refund Revenue Bonds Outstanding Value      
Debt Instrument [Line Items]      
Other Long-Term Debt, Current $ 60,000    
Subsidiaries [Member]      
Debt Instrument [Line Items]      
Long-term Debt   3,037,613 3,037,074
Subsidiaries [Member] | FMB Twenty - four      
Debt Instrument [Line Items]      
Secured Debt   $ 55,000 55,000
Debt Instrument, Interest Rate, Stated Percentage   1.40%  
Subsidiaries [Member] | FMB Twenty Seven      
Debt Instrument [Line Items]      
Secured Debt   $ 650,000 650,000
Debt Instrument, Interest Rate, Stated Percentage   5.70%  
Parent Company [Member] | Three Point Four Five Percent Senior Secured Notes [Member]      
Debt Instrument [Line Items]      
Long-term Debt   $ 475,000 475,000
Debt Instrument, Interest Rate, Stated Percentage   4.25%  
Line of Credit [Member] | Committed Line of Credit [Member]      
Debt Instrument [Line Items]      
Line of credit, outstanding borrowings   $ 30,000 $ 0