Debt (Credit Facilities) (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2018 USD ($) extension	Jan. 31, 2022 USD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Balance availability under Credit Facilities	$ 2,633,800,000			$ 1,671,800,000
Letters of credit outstanding under our Credit Facilities	341,900,000			376,500,000
Long-term debt	9,678,300,000
Credit facilities: Uncommitted facility
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity	135,000,000
Long-term debt	0			0
Credit facilities: Uncommitted facility | Subsequent Event
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity			$ 200,000,000
Line Of Credit Due August 2026
Line of Credit Facility [Line Items]
Long-term debt	24,300,000			0
Credit facilities: June 2023
Line of Credit Facility [Line Items]
Long-term debt	0			186,000,000.0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings outstanding from Credit Facilities	24,300,000			$ 186,000,000
Line of Credit | Line Of Credit Due August 2026
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity	3,000,000,000
Line of Credit | Credit facilities: June 2023
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity	$ 2,250,000,000
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Number of available extensions | extension		2
Extension period		1 year
Accordion feature, increase limit (up to)		$ 1,000,000,000
Basis spread on variable rate	0.91%