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Senior, Senior Subordinated, Convertible Senior Notes (Details Textual) (USD $)
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12 Months Ended | 12 Months Ended | ||||||||||||||||||
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2012
6.25% senior notes due 2015 [Member]
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Apr. 30, 2012
6.25% senior notes due 2015 [Member]
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Dec. 31, 2011
6.25% senior notes due 2015 [Member]
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Dec. 31, 2012
7.731% senior subordinated notes due 2017 [Member]
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Apr. 30, 2012
7.731% senior subordinated notes due 2017 [Member]
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Dec. 31, 2011
7.731% senior subordinated notes due 2017 [Member]
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Dec. 31, 2012
7.00% senior notes due 2022 [Member]
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Apr. 30, 2012
7.00% senior notes due 2022 [Member]
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Dec. 31, 2012
7.15% senior notes due 2020 [Member]
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Dec. 31, 2011
7.15% senior notes due 2020 [Member]
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Dec. 31, 2012
1.875% convertible senior notes due 2032 [Member]
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Dec. 31, 2012
Revolving Credit Facility [Member]
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Dec. 31, 2011
Revolving Credit Facility [Member]
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Jan. 01, 2013
Consolidated EBITDA [Member]
Revolving Credit Facility [Member]
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Dec. 31, 2012
Consolidated EBITDA [Member]
Revolving Credit Facility [Member]
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Jan. 01, 2013
Consolidated Interest Incurred [Member]
Revolving Credit Facility [Member]
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Dec. 31, 2012
Consolidated Interest Incurred [Member]
Revolving Credit Facility [Member]
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| Debt Instrument [Line Items] | ||||||||||||||||||||
| Debt instrument, stated rate | 6.25% | 7.731% | 7.731% | 7.00% | 7.15% | 7.15% | 1.875% | |||||||||||||
| Percentage of wholly owned subsidiary | 100.00% | |||||||||||||||||||
| Aggregate principal amount of offering | $ 300,000,000 | $ 126,500,000 | ||||||||||||||||||
| Aggregate principal amount repurchased | 285,000,000 | 26,100,000 | ||||||||||||||||||
| Loss on extinguishment of debt, net of transaction costs | (5,772,000) | 0 | (3,454,000) | |||||||||||||||||
| Line of credit facility, maximum borrowing capacity | 50,000,000 | 125,000,000 | ||||||||||||||||||
| Available for issuance | 50,000,000 | |||||||||||||||||||
| Minimum net worth required for compliance | 360,000,000 | |||||||||||||||||||
| Leverage ratio | 60.00% | |||||||||||||||||||
| Interest coverage ratio | 1.50 | 1.00 | 1.00 | 1.00 | ||||||||||||||||
| Line of credit facility, amount outstanding | 0 | 0 | 0 | |||||||||||||||||
| Senior notes unamortized discount | 0 | 451,000 | 3,528,000 | 4,015,000 | ||||||||||||||||
| Year in which senior and senior subordinated notes due | 2015 | 2017 | 2017 | 2022 | 2020 | 2020 | 2032 | |||||||||||||
| Debt instrument, convertible, conversion ratio | 17.1985 | |||||||||||||||||||
| Conversion principal amount | 1,000 | |||||||||||||||||||
| Debt instrument, convertible, conversion price | $ 58.14 | |||||||||||||||||||
| Conversion premium | 47.50% | |||||||||||||||||||
| Restricted Cash and Cash Equivalents | $ 38,938,000 | $ 12,146,000 | ||||||||||||||||||