Amortized Cost and Fair Value of Available for Sale Securities by Expected Maturity (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Amortized Cost [Abstract]
Due in one year or less	$ 657,850	$ 677,453
Due after one year through five years	5,551,701	5,330,696
Due after five years through ten years	2,764,758	2,886,333
Due after ten years	3,441	3,686
Total amortized cost	8,977,750	8,898,168
Fair Value [Abstract]
Due in one year or less	661,992	682,965
Due after one year through five years	5,705,691	5,533,074
Due after five years through ten years	2,760,188	2,978,301
Due after ten years	3,681	3,952
Total fair value	$ 9,131,552	$ 9,198,292