Debt (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Debt Instrument [Line Items]
Long-term Debt	$ 3,635,037	$ 3,003,420
Proceeds from Secured Lines of Credit	300,000
Letters of Credit Outstanding, Amount	300,000
FMB Twenty Seven
Debt Instrument [Line Items]
Secured Debt	650,000
Subsidiaries [Member]
Debt Instrument [Line Items]
Long-term Debt	2,769,880	2,128,293
Secured Debt	2,769,880	2,128,293
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 - five
Debt Instrument [Line Items]
Secured Debt	$ 40,000	40,000
Debt Instrument, Interest Rate, Stated Percentage	0.65%
Subsidiaries [Member] | FMB Twenty Seven
Debt Instrument [Line Items]
Secured Debt	$ 650,000	0
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Subsidiaries [Member] | $400M Term Loan
Debt Instrument [Line Items]
Short-Term Bank Loans and Notes Payable	$ 400,000
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%
Parent Company [Member] | Three Point Seven Zero Percent Senior Secured Notes [Domain]
Debt Instrument [Line Items]
Long-term Debt	$ 0	$ 405,000
Debt Instrument, Interest Rate, Stated Percentage	3.70%
Line of Credit [Member] | Committed Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit, outstanding borrowings	$ 50,000		$ 155,000