Temporarily Impaired Available for Sale Securities by Time Period Impaired (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 29, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 118,764	$ 593,647
Less Than 12 Months, Unrealized Losses	4,840	18,968
12 Months or Longer, Fair Value	17,396	7,915
12 Months or Longer, Unrealized Losses	4,904	389
Total, Fair Value	136,160	601,562
Total, Unrealized Losses	9,744	19,357
Tax exempt bonds
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	19,113	138,892
Less Than 12 Months, Unrealized Losses	10	536
12 Months or Longer, Fair Value		6,026
12 Months or Longer, Unrealized Losses		14
Total, Fair Value	19,113	144,918
Total, Unrealized Losses	10	550
Taxable bonds
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	42,103	201,538
Less Than 12 Months, Unrealized Losses	43	1,514
Total, Fair Value	42,103	201,538
Total, Unrealized Losses	43	1,514
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	57,548	86,236
Less Than 12 Months, Unrealized Losses	4,787	13,899
12 Months or Longer, Fair Value	17,396	1,889
12 Months or Longer, Unrealized Losses	4,904	375
Total, Fair Value	74,944	88,125
Total, Unrealized Losses	9,691	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