Amortized Cost and Fair Value of Available for Sale Securities by Expected Maturity (Detail) - USD ($) $ in Thousands	Jun. 25, 2016	Dec. 26, 2015
Amortized Cost
Due in one year or less	$ 1,462,861	$ 1,375,450
Due after one year through five years	3,972,098	3,951,600
Due after five years through ten years	381,423	161,732
Due after ten years	20,042	62,425
Total	5,836,424	5,551,207
Amortized cost of available-for-sale securities	6,899,595	6,551,908
Fair Value
Due in one year or less	1,464,791	1,376,698
Due after one year through five years	4,002,436	3,948,654
Due after five years through ten years	385,783	162,999
Due after ten years	20,908	63,250
Total	5,873,918	5,551,601
Fair value of available-for-sale securities	6,997,117	6,602,934
Restricted investments
Amortized Cost
Amortized cost of available-for-sale securities	164,549	164,548
Fair Value
Fair value of available-for-sale securities	165,938	163,159
Equity securities
Amortized Cost
Amortized cost of available-for-sale securities	898,622	836,153
Fair Value
Fair value of available-for-sale securities	$ 957,261	$ 888,174