Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands |
Jun. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Property, plant, and equipment, accumulated depreciation | $ 32,801 | $ 31,588 |
| Leased property, net of accumulated depreciation | 16,394 | 11,812 |
| Intangible assets, net of accumulated amortization | $ 2,036 | $ 1,735 |
| Common Stock, par value (in dollars per share) | $ 0.01 | $ 0.01 |
| Common Stock, shares authorized | 750,000,000 | 750,000,000 |
| Common Stock, shares issued | 229,655,825 | 229,073,517 |
| Common stock in treasury, shares | 15,002,663 | 587,151 |
| Series C Redeemable Convertible Preferred Stock | ||
| Redeemable convertible Preferred Stock, par value (in dollars per share) | $ 0.01 | $ 0.01 |
| Redeemable convertible Preferred Stock, shares authorized | 10,431 | 10,431 |
| Redeemable convertible Preferred Stock, shares issued | 2,620 | 2,620 |
| Redeemable convertible Preferred Stock, shares outstanding | 2,620 | 2,620 |
| Redeemable convertible Preferred Stock, aggregate involuntary liquidation preference (in dollars) | $ 16,664 | $ 16,664 |