Note 6 - Financing Arrangements (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Nov. 30, 2011
Debt Instrument, Face Amount	$ 172,500,000
Line of Credit Facility, Maximum Borrowing Capacity				125,000,000
Line of Credit Facility, Increase, Additional Borrowings	75,000,000
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Debt Conversion Converted Instrument Shares Issued For Basis Principal (in Shares)	90.8893
Debt Conversion Principal Amount Of Senior Notes As Basis For Conversion Rate	1,000
Debt Instrument, Convertible, Conversion Price (in Dollars per share)	$ 11.00
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)	2.00%
Debt Instrument, Additional Basis Spread On Variable Rate, Minimum (in Basis Points)	0.75%
Debt Instrument, Additional Basis Spread On Variable Rate, Maximum (in Basis Points)	2.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage (in Basis Points)	0.375%
Line of Credit Facility, Amount Outstanding	84,000,000	17,000,000
Line of Credit Facility, Remaining Borrowing Capacity	34,100,000
Letters Of Credit, Outstanding Relating To Foreign Operations	200,000
Short-term Debt, Weighted Average Interest Rate	2.81%	3.54%
Short-term Debt	2,599,000	2,232,000
Interest Expense	9,740,000	9,226,000	10,267,000
Approximation [Member]
Short-term Debt	2,500,000	2,200,000
Minimum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	125,000,000
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)	1.75%
Maximum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	200,000,000
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)	3.00%
Federal Funds Rate [Member]
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)	0.50%
Eurodollar Rate [Member]
Debt Instrument, Basis Spread on Variable Rate (in Basis Points)	1.00%
Letter of Credit [Member]
Line of Credit Facility, Amount Outstanding	$ 6,900,000