The number of consecutive trading days ending on the last trading day of the immediately preceding calendar quarter in which 20 trading days of which our last reported price of common stock is greater than or equal to 130% of the conversion price of convertible debt.

No definition available.

Notes Payable and Amounts Due Under Repurchase Agreements (2015 Notes, 2015 Notes Hedges and 2015 Warrants Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010	Sep. 30, 2010
Debt Instrument [Line Items]
Interest expense on convertible notes	$ 36,370,000us-gaap_InterestExpenseDebt	$ 38,870,000us-gaap_InterestExpenseDebt	$ 28,479,000us-gaap_InterestExpenseDebt
Convertible Debt [Member]
Debt Instrument [Line Items]
Interest expense on convertible notes	9,000,000	26,400,000	28,500,000
2015 Notes Embedded Conversion Derivative [Member]
Debt Instrument [Line Items]
Derivative, liability, fair value at issuance	37,000,000
September 2015 Notes [Member]
Debt Instrument [Line Items]
Principal amount of convertible senior notes payable at issuance					200,000,000
Interest rate	3.50%
Deferred financing costs	6,800,000
Debt instrument, number of days holders may convert	5 days
Debt instrument, measurement period of convertible senior notes	10 days
Debt instrument, face amount	1,000
Product of last reported common stock sale price and conversion rate	98.00%
Debt instrument, number of days to measure stock value against conversion value	20 days
Debt instrument, consecutive trading day period to determine convertibility	30 days
Stock price must exceed conversion price to allow conversion	130.00%
Debt instrument, convertible, number of equity instruments, shares			80.9486	80
Debt instrument, convertible, conversion price			$ 12.35	$ 12.50
Debt instrument, convertible, fundamental change stock price floor	$ 10.00
Debt instrument, convertible, conversion rate increase upon fundamental change	20
Extinguishment of debt, amount		108,000,000
Extinguishment of debt, cash paid		116,100,000
Extinguishment of debt, cash paid for shares of common stock		79,200,000
Extinguishment of debt, shares issued		3,643,402
Extinguishment of debt, carrying value at extinguishment		99,600,000
Extinguishment of debt, gain (loss), net of tax		(15,200,000)
Interest rate, effective percentage	8.90%
September 2015 Notes [Member] \| Private Exchange Offers [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount	69,600,000
Extinguishment of debt, cash paid	82,900,000
Extinguishment of debt, cash paid for shares of common stock	48,200,000
Extinguishment of debt, shares issued	2,115,055
Extinguishment of debt, carrying value at extinguishment	66,000,000
Extinguishment of debt, gain (loss), net of tax	$ (4,800,000)
September 2015 Notes [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, convertible, threshold for adjustment of conversion rate and conversion price	1.00%