Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 30, 2018 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | $ 427,797 | $ 371,301 |
Long-term AFS securities | 162,911 | 213,558 |
Total long term debt | 247,000 | 247,000 |
Long-term debt, fair value | 251,000 | 260,000 |
Level 1 | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Deferred compensation | 22,132 | 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 | 22,132 | 23,211 |
Debt Securities | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 427,797 | 371,301 |
Long-term AFS securities | 162,911 | 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 | 427,797 | 371,301 |
Long-term AFS securities | 162,911 | 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 |
U.S. Treasury securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 144,480 | 107,485 |
Long-term AFS securities | 27,157 | 46,737 |
U.S. Treasury securities | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 144,480 | 107,485 |
Long-term AFS securities | 27,157 | 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 | 144,480 | 107,485 |
Long-term AFS securities | 27,157 | 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 |
Corporate debt securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 120,937 | 140,168 |
Long-term AFS securities | 104,477 | 129,624 |
Corporate debt securities | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 120,937 | 140,168 |
Long-term AFS securities | 104,477 | 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 | 120,937 | 140,168 |
Long-term AFS securities | 104,477 | 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. governmental agency securities | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 108,820 | 91,974 |
Long-term AFS securities | 31,277 | 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 | 108,820 | 91,974 |
Long-term AFS securities | 31,277 | 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 |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 35,063 | 8,177 |
Commercial paper | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 35,063 | 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 | 35,063 | 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 |
Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 18,497 | 23,497 |
Certificates of deposit | Recurring | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term AFS securities | 18,497 | 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 | 18,497 | 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 |
Life Insurance Product Line [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Life Insurance Investments | $ 43,100 | $ 38,100 |