Financing Agreements (Financing Agreements, at Fair Values Narrative) (Details) - USD ($) $ in Thousands		6 Months Ended
	Jun. 26, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Agreements [Line Items]
Agreement amount		$ 5,047,981	$ 10,044,844
Financial instruments		5,011,356	$ 10,031,606
Senior secured credit agreement
Financing Agreements [Line Items]
Agreement amount		500,000
Financial instruments		480,959
Agreements with mark-to-market collateral provisions
Financing Agreements [Line Items]
Agreement amount		1,656,248
Financial instruments	$ 1,650,000	1,656,248
Agreements with non-mark-to-market collateral provisions
Financing Agreements [Line Items]
Agreement amount		2,036,597
Financial instruments		2,036,597
Non Mark to Market Financing Facilities
Financing Agreements [Line Items]
Financial instruments		1,600,000
Debt instrument term	2 years
Non Mark to Market Financing Facilities on Rehabilitation Loans
Financing Agreements [Line Items]
Debt outstanding		$ 474,600
Minimum | Agreements with mark-to-market collateral provisions
Financing Agreements [Line Items]
Debt instrument term		1 month
Maximum | Agreements with mark-to-market collateral provisions
Financing Agreements [Line Items]
Debt instrument term		3 months