| **Convertible Perpetual Preferred Stock**            | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
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| **Convertible Perpetual Preferred Stock [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Convertible Perpetual Preferred Stock                | Convertible Perpetual Preferred Stock:On March 7, 2006, we completed the sale of 400,000 shares of our 6.50% Series A Convertible Perpetual Preferred Stock. The preferred stock has an initial liquidation preference of $1,000 per share of preferred stock, which is contingently subject to accretion. Holders of the preferred stock are entitled to receive, when and if declared by our board of directors, cash dividends at the rate of 6.50% per annum on the accreted liquidation preference per share, payable quarterly in arrears. Dividends on the preferred stock are cumulative. Each holder of preferred stock has one vote for each share held by the holder on all matters voted upon by the holders of our common stock.The preferred stock is convertible, at the option of the holder, at any time into shares of our common stock at an initial conversion price of $30.50 per share, which is equal to an initial conversion rate of approximately 32.7869 shares of common stock per share of preferred stock, subject to specified adjustments. We may at any time cause the shares of preferred stock to be automatically converted into shares of our common stock at the conversion rate then in effect if the closing sale price of our common stock for 20 trading days within a period of 30 consecutive trading days ending on the trading day before the date we give the notice of forced conversion exceeds 150% of the conversion price of the preferred stock. If we are subject to a fundamental change, as defined in the certificate of designation of the preferred stock, each holder of shares of preferred stock has the right, subject to certain limitations, to require us to purchase with cash any or all of its shares of preferred stock at a purchase price equal to 100% of the accreted liquidation preference, plus any accrued and unpaid dividends to the date of purchase. In addition, if holders of the preferred stock elect to convert shares of preferred stock in connection with certain fundamental changes, we will in certain circumstances increase the conversion rate for such shares of preferred stock. As redemption of the preferred stock is contingent upon the occurrence of a fundamental change, and since we do not deem a fundamental change probable of occurring, accretion of our Convertible perpetual preferred stock is not necessary.  We declared $26.0 million in dividends on our preferred stock in each of the three years ended December 31, 2011. As of December 31, 2011 and 2010, accrued dividends of $6.5 million were included in Other current liabilities on our consolidated balance sheets. These accrued dividends were paid in January 2012 and 2011. |

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| - Definition
The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to preferred stock.
+ References
No definition available.
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