Note 11 - Income Taxes (Details Textual) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 20, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Mar. 31, 2017
Deferred Tax Liabilities, Undistributed Foreign Earnings		$ 110.5		$ 110.5
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		(62.0)
Accrued Estimated Foreign Tax Withholdings		53.9		53.9
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		109.6		109.6
Deferred Tax Assets, Valuation Allowance		$ 48.0		$ 48.0			$ 109.6
Effective Income Tax Rate Reconciliation, Percent		14.20%	23.20%	17.70%	23.10%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%		35.00%
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount		$ 0.8	$ 1.1	$ 1.7	$ 2.3
Undistributed Earnings of Foreign Subsidiaries						$ 367.0
Investment Tax Credit Carryforward [Member]
Deferred Tax Assets, Investments						$ 0.7
Tax Credit Carryforward Expiration Period						20 years
General Business Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Period						20 years
Minimum [Member] | Investment Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Year						2022
Minimum [Member] | General Business Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Year						2026
Maximum [Member] | Investment Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Year						2024
Maximum [Member] | General Business Tax Credit Carryforward [Member]
Deferred Tax Assets, Tax Credit Carryforwards, General Business						$ 82.5
Tax Credit Carryforward Expiration Year						2036
Domestic Tax Authority [Member]
Operating Loss Carryforwards						$ 299.6
Domestic Tax Authority [Member] | Minimum [Member]
Tax Credit Carryforward Expiration Year						2029
Domestic Tax Authority [Member] | Maximum [Member]
Tax Credit Carryforward Expiration Year						2036
State and Local Jurisdiction [Member]
Operating Loss Carryforwards						$ 244.7
State and Local Jurisdiction [Member] | Minimum [Member]
Tax Credit Carryforward Expiration Year						2018
State and Local Jurisdiction [Member] | Maximum [Member]
Tax Credit Carryforward Expiration Year						2036
Foreign Tax Authority [Member] | Kenya Revenue Authority [Member]
Income Tax Examination, Penalties Paid	$ 2.6
Investment Deduction Percentage	150.00%
Income Tax Examination, Interest Expense	$ 1.2
ISRAEL
National Corporate Tax Rate				16.00%
KENYA
National Corporate Tax Rate				37.50%
U.S. Foreign Tax Credits [Member]
Deferred Tax Assets, Valuation Allowance		40.8		$ 40.8
Current Year Projected Activity [Member]
Deferred Tax Assets, Valuation Allowance		$ 7.0		$ 7.0