Note 17 - Weighted-average Asset Allocation By Assets Category (Details)	Dec. 31, 2017	Dec. 31, 2016
Major US Plans [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	100.00%	100.00%
Major US Plans [Member] | Equity Securities [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	10.00%	16.00%
Major US Plans [Member] | Equity Securities [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	7.00%
Major US Plans [Member] | Equity Securities [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	13.00%
Major US Plans [Member] | Debt Securities [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	42.00%	33.00%
Major US Plans [Member] | Debt Securities [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	35.00%
Major US Plans [Member] | Debt Securities [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	45.00%
Major US Plans [Member] | Real Estate [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	2.00%	3.00%
Major US Plans [Member] | Real Estate [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	0.00%
Major US Plans [Member] | Real Estate [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	6.00%
Major US Plans [Member] | Cash and Cash Equivalents [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	1.00%	3.00%
Major US Plans [Member] | Cash and Cash Equivalents [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	0.00%
Major US Plans [Member] | Cash and Cash Equivalents [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	6.00%
Major US Plans [Member] | Global Balanced Asset Allocation Funds [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	16.00%	14.00%
Major US Plans [Member] | Global Balanced Asset Allocation Funds [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	12.00%
Major US Plans [Member] | Global Balanced Asset Allocation Funds [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	18.00%
Major US Plans [Member] | Other Assets [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	29.00%	31.00%
Major US Plans [Member] | Other Assets [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	27.00%
Major US Plans [Member] | Other Assets [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	39.00%
Major Non-U.S. Plans [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	100.00%	100.00%
Major Non-U.S. Plans [Member] | Equity Securities [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	3.00%	4.00%
Major Non-U.S. Plans [Member] | Equity Securities [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	0.00%
Major Non-U.S. Plans [Member] | Equity Securities [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	6.00%
Major Non-U.S. Plans [Member] | Debt Securities [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	32.00%	31.00%
Major Non-U.S. Plans [Member] | Debt Securities [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	30.00%
Major Non-U.S. Plans [Member] | Debt Securities [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	40.00%
Major Non-U.S. Plans [Member] | Real Estate [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	1.00%	1.00%
Major Non-U.S. Plans [Member] | Real Estate [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	0.00%
Major Non-U.S. Plans [Member] | Real Estate [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	6.00%
Major Non-U.S. Plans [Member] | Cash and Cash Equivalents [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	2.00%	3.00%
Major Non-U.S. Plans [Member] | Cash and Cash Equivalents [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	0.00%
Major Non-U.S. Plans [Member] | Cash and Cash Equivalents [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	6.00%
Major Non-U.S. Plans [Member] | Global Balanced Asset Allocation Funds [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	5.00%	4.00%
Major Non-U.S. Plans [Member] | Global Balanced Asset Allocation Funds [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	2.00%
Major Non-U.S. Plans [Member] | Global Balanced Asset Allocation Funds [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	8.00%
Major Non-U.S. Plans [Member] | Other Assets [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Asset allocations	57.00%	57.00%
Major Non-U.S. Plans [Member] | Other Assets [Member] | Minimum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	55.00%
Major Non-U.S. Plans [Member] | Other Assets [Member] | Maximum [Member]
Weighted Average Asset Allocation By Assets Category [Line Items]
Target asset allocations	65.00%