Schedule of Cash, Cash Equivalents, Investments and Restricted Cash and Investments Unrealized Loss Positions (Detail) $ in Thousands	Dec. 27, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	$ 1,937,479
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(9,621)
Unrealized Losses 12 Months or Greater - Fair Value	55,714
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(350)
Total - Fair Value	1,993,193
Total - Gross Unrealized Loss	(9,971)
Municipal Notes and Bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	256,272
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(313)
Unrealized Losses 12 Months or Greater - Fair Value	1,816
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(4)
Total - Fair Value	258,088
Total - Gross Unrealized Loss	(317)
U.S. Treasury & Agencies
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	347,138
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(2,051)
Total - Fair Value	347,138
Total - Gross Unrealized Loss	(2,051)
Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	22,053
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(573)
Total - Fair Value	22,053
Total - Gross Unrealized Loss	(573)
Government-Sponsored Enterprises
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	47,507
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(270)
Total - Fair Value	47,507
Total - Gross Unrealized Loss	(270)
Foreign Government Bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	39,895
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(229)
Total - Fair Value	39,895
Total - Gross Unrealized Loss	(229)
Corporate Notes and Bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	1,107,398
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(5,252)
Unrealized Losses 12 Months or Greater - Fair Value	39,808
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(149)
Total - Fair Value	1,147,206
Total - Gross Unrealized Loss	(5,401)
Mortgage Backed Securities — Residential
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	23,303
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(279)
Unrealized Losses 12 Months or Greater - Fair Value	1,669
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(92)
Total - Fair Value	24,972
Total - Gross Unrealized Loss	(371)
Mortgage Backed Securities — Commercial
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Less Than 12 Months - Fair Value	93,913
Unrealized Losses Less Than 12 Months - Gross Unrealized Loss	(654)
Unrealized Losses 12 Months or Greater - Fair Value	12,421
Unrealized Losses 12 Months or Greater - Gross Unrealized Loss	(105)
Total - Fair Value	106,334
Total - Gross Unrealized Loss	$ (759)