Notes Payable Convertible Debt Issued in 2004 (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Loss on Extinguishment of Debt	$ 0	$ 0	$ (292,000)
Convertible Debt Issued in 2009 [Member]
Debt Instrument [Line Items]
Principal Amount of Convertible Senior Notes Payable at Issuance	115,800,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	15,600,000
Deferred Income Tax Liability, Equity Component of Convertible Debt	11,000,000
Debt Instrument, Convertible, Conversion Price	$ 9.57
Debt Instrument, Convertible, Number of Shares	104.5
Convertible Debt Issued in 2004 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	8.50%
Debt Instrument, Face Amount	1,000
Principal Amount of Convertible Senior Notes Payable, Extinguished in Exchange for Subsequent Issuance			63,600,000
Principal Amount of Convertible Senior Notes Payable at Issuance	260,000,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	22,900,000
Deferred Income Tax Liability, Equity Component of Convertible Debt	16,100,000
Debt Instrument, Interest Rate, Stated Percentage	5.25%
Convetible Senior Notes, Contingent Interest Rate	0.50%
Number of Days to Measure Stock Value Against Conversion Value	20
Consecutive Trading Day Period to Determine Convertibility	30
Stock Price Must Exceed Conversion Price to Allow Conversion	120.00%
Debt Instrument, Convertible, Conversion Price	$ 13.74
Debt Instrument, Convertible, Number of Shares	72.8
Extinguishment of Debt, Amount		6,700,000
Loss on Extinguishment of Debt		300,000
Exchange of Debt, Unamortized Discount and Issue Costs of Extinguished Debt		300,000
Extinguishment of Debt, Cash Paid		$ 6,600,000