Temporarily Impaired Available for Sale Securities by Time Period Impaired (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 29, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 858,549	$ 593,647
Less Than 12 Months, Unrealized Losses	11,879	18,968
12 Months or Longer, Fair Value	14,260	7,915
12 Months or Longer, Unrealized Losses	3,621	389
Total, Fair Value	872,809	601,562
Total, Unrealized Losses	15,500	19,357
Tax exempt bonds
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	566,914	138,892
Less Than 12 Months, Unrealized Losses	2,646	536
12 Months or Longer, Fair Value		6,026
12 Months or Longer, Unrealized Losses		14
Total, Fair Value	566,914	144,918
Total, Unrealized Losses	2,646	550
Taxable bonds
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	81,876	201,538
Less Than 12 Months, Unrealized Losses	355	1,514
Total, Fair Value	81,876	201,538
Total, Unrealized Losses	355	1,514
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	209,759	86,236
Less Than 12 Months, Unrealized Losses	8,878	13,899
12 Months or Longer, Fair Value	14,260	1,889
12 Months or Longer, Unrealized Losses	3,621	375
Total, Fair Value	224,019	88,125
Total, Unrealized Losses	12,499	14,274
Restricted investments
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value		166,981
Less Than 12 Months, Unrealized Losses		3,019
Total, Fair Value		166,981
Total, Unrealized Losses		$ 3,019