Note 15 - Redeemable, Convertible Series A Preferred Stock (Details Textual) - USD ($) $ / shares in Units, $ in Millions		6 Months Ended
	Nov. 15, 2016	Jun. 30, 2018
Series A Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock, number of shares issued	2,000,000
Percentage of cash dividend payable on preferred stock	5.50%
Preferred stock, no par value	$ 0
Gross proceeds from issuance of shares	$ 200
Preferred stock, liquidation preference per share	$ 100
Series A Preferred Stock [Member]
Temporary Equity [Line Items]
Percentage of cash dividend payable on preferred stock	5.50%
Net proceeds received to derivative liability	$ 43
Carrying value of Series A preferred stock at issuance	155
Gross proceeds from preferred stock	200
Fair value of derivative liability	43
Transaction costs	$ 2
Preferred stock, redemption date	Nov. 15, 2021
Preferred stock, redemption price per share	$ 100
Preferred stock conversion description		As of June 30, 2018, the Series A Preferred Stock has not been converted and none of the antidilution provisions have been triggered. Any shares of Series A Preferred Stock not converted prior to the fifth anniversary of the initial issuance of the Series A Preferred Stock are required to be redeemed at $100 per share plus the amount of accrued and unpaid dividends.