Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	$ 388,077	$ 371,301
Long-term AFS securities	185,083	213,558
Total long term debt	248,000	247,000
Long-term debt, fair value	259,000	260,000
Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	21,447	23,211
Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	0	0
Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	0	0
Fair Value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	21,447	23,211
Debt Securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	388,077	371,301
Long-term AFS securities	185,083	213,558
Debt Securities | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
Debt Securities | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	388,077	371,301
Long-term AFS securities	185,083	213,558
Debt Securities | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	141,145	140,168
Long-term AFS securities	107,292	129,624
Corporate debt securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	141,145	140,168
Long-term AFS securities	107,292	129,624
Corporate debt securities | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
Corporate debt securities | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	141,145	140,168
Long-term AFS securities	107,292	129,624
Corporate debt securities | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	121,067	107,485
Long-term AFS securities	38,561	46,737
U.S. Treasury securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	121,067	107,485
Long-term AFS securities	38,561	46,737
U.S. Treasury securities | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
U.S. Treasury securities | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	121,067	107,485
Long-term AFS securities	38,561	46,737
U.S. Treasury securities | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
U.S. governmental agency securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	87,819	91,974
Long-term AFS securities	39,230	37,197
U.S. governmental agency securities | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
U.S. governmental agency securities | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	87,819	91,974
Long-term AFS securities	39,230	37,197
U.S. governmental agency securities | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Long-term AFS securities	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	21,688	23,497
Certificates of deposit | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	21,688	23,497
Certificates of deposit | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Certificates of deposit | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	21,688	23,497
Certificates of deposit | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	16,358	8,177
Commercial paper | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	16,358	8,177
Commercial paper | Level 1 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Commercial paper | Level 2 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	16,358	8,177
Commercial paper | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term AFS securities	0	0
Life Insurance Product Line [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Miscellaneous	$ 41,800	$ 38,100