Investments Equity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Equity Securities [Line Items]
Equity Securities, FV-NI	$ 2,887,601	$ 2,547,180
Equity Securities [Member]
Equity Securities [Line Items]
Equity Securities, FV-NI	2,725,368	2,383,095
Equity Securities, Restricted [Member]
Equity Securities [Line Items]
Equity Securities, FV-NI, Restricted	$ 162,233	$ 164,085