Available for Sale Securities (Detail) (USD $)	Mar. 29, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 6,308,207,000	$ 5,836,904,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	182,689,000	172,348,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	14,294,000	17,766,000
Fair Value	6,476,602,000	5,991,486,000
Tax exempt bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,530,137,000	3,430,028,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	24,465,000	25,588,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	7,346,000	9,917,000
Fair Value	3,547,256,000	3,445,699,000
Taxable bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,692,999,000	1,445,901,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	8,051,000	7,641,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	2,778,000	3,863,000
Fair Value	1,698,272,000	1,449,679,000
Restricted investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	170,000,000	170,000,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	431,000	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	86,000
Fair Value	170,431,000	169,914,000
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	915,071,000	790,975,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	149,742,000	139,119,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	4,170,000	3,900,000
Fair Value	$ 1,060,643,000	$ 926,194,000