Note 8 - Borrowings (Details Textual) € in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2016 EUR (€)	Dec. 31, 2017 USD ($)	Jan. 01, 2017 USD ($)	Jan. 03, 2016 USD ($)
Threshold Of Other Indebtedness Triggering Default			$ 20,000,000
Long-term Debt			229,928,000
Debt Issuance Costs, Net			2,300,000	$ 1,400,000
Amortization of Debt Issuance Costs and Discounts			500,000	500,000	$ 500,000
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net			0
Derivative, Notional Amount			100,000,000
Interest Rate Swap [Member] | Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			0
Interest Rate Swap [Member] | Other Assets [Member]
Derivative Asset, Fair Value, Gross Asset			900,000
Syndicated Facility Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity			250,000,000
Line of Credit Facility, Option to Increase Maximum Borrowing Capacity, Amount			$ 150,000,000
Maximum Percentage Of First Tier Subsidiary Stock Pledged As Collateral			65.00%
Long-term Line of Credit			$ 59,900,000
Letters of Credit Outstanding, Amount			$ 6,000,000
Long-term Debt, Weighted Average Interest Rate, at Point in Time			3.00%
Syndicated Facility Agreement [Member] | One of the Company's Foreign Subsidiaries [Member]
Proceeds from Lines of Credit	$ 63,500,000	€ 61
Syndicated Facility Agreement [Member] | For Each Fiscal Quarter Thereafter [Member]
Maximum Consolidated Net Leverage Ratio			3.75
Minimum Consolidated Interest Coverage Ratio			2.25
Syndicated Facility Agreement [Member] | Federal Funds Rate [Member]
Debt Instrument, Basis Spread on Variable Rate			0.50%
Syndicated Facility Agreement [Member] | Minimum [Member]
Line of Credit Facility, Interest Rate During Period			0.25%
Line of Credit Facility, Commitment Fee Percentage			0.20%
Syndicated Facility Agreement [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			1.25%
Syndicated Facility Agreement [Member] | Maximum [Member]
Line of Credit Facility, Interest Rate During Period			1.50%
Line of Credit Facility, Commitment Fee Percentage			0.35%
Syndicated Facility Agreement [Member] | Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			2.50%
Syndicated Facility Agreement [Member] | Term Loan A [Member]
Debt Instrument, Face Amount			$ 177,500,000
Debt Instrument, Periodic Payment			3,750,000
Long-term Debt			170,000,000
Syndicated Facility Agreement [Member] | Standby Letters of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity			40,000,000
Other Line Of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity			9,800,000
Long-term Line of Credit			$ 0	$ 0
Other Line Of Credit [Member] | Minimum [Member]
Line of Credit Facility, Interest Rate During Period			2.50%
Other Line Of Credit [Member] | Maximum [Member]
Line of Credit Facility, Interest Rate During Period			6.50%