v2.4.0.8
Marketable Securities (Schedule of Available-for-sale-securities Unrealized Loss on Investments) (Details) (USD $)
In Thousands, unless otherwise specified
 6 Months Ended
Jun. 28, 2014
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months $ (2,969)
Gross Unrealized Losses 12 Consecutive Months or Longer (23,895)
Fair Value  
Fair Value Less than 12 Consecutive Months 390,600
Fair Value 12 Consecutive Months or Longer 609,232
Mortgage-Backed Securities [Member]
  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (446)
Gross Unrealized Losses 12 Consecutive Months or Longer (9,816)
Fair Value  
Fair Value Less than 12 Consecutive Months 57,696
Fair Value 12 Consecutive Months or Longer 204,669
Obligations of States and Political Subdivisions [Member]
  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (468)
Gross Unrealized Losses 12 Consecutive Months or Longer (11,821)
Fair Value  
Fair Value Less than 12 Consecutive Months 82,370
Fair Value 12 Consecutive Months or Longer 318,318
U.S. Corporate Bonds [Member]
  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (2,005)
Gross Unrealized Losses 12 Consecutive Months or Longer (2,245)
Fair Value  
Fair Value Less than 12 Consecutive Months 232,032
Fair Value 12 Consecutive Months or Longer 83,073
Common Stock [Member]
  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (15)
Gross Unrealized Losses 12 Consecutive Months or Longer 0
Fair Value  
Fair Value Less than 12 Consecutive Months 5,797
Fair Value 12 Consecutive Months or Longer 0
Other [Member]
  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (35)
Gross Unrealized Losses 12 Consecutive Months or Longer (13)
Fair Value  
Fair Value Less than 12 Consecutive Months 12,705
Fair Value 12 Consecutive Months or Longer $ 3,172