Investments and Fair Value Measurements Fair Value Inputs, Quantitative Information (Details) (Significant Unobservable Inputs (Level 3), Fair Value, Measurements, Recurring [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013 years	Dec. 31, 2012 years
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Warrants	$ 806	$ 769
Fair value of derivatives embedded within convertible debt	166,629	172,128
Option Model [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Warrants	806	769
Discounted Cash Flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair value of derivatives embedded within convertible debt	$ 166,629	$ 172,128
Warrants | Option Model [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Stock price (dollars per share)	$ 1.54	$ 1.40
Exercise price (dollars per share)	$ 1.68	$ 1.68
Term (in years)	4.4	3.8
Volatility	95.19%	76.87%
Dividend rate	0.00%	0.00%
Risk-free return	0.64%	0.50%
Derivative Financial Instruments, Liabilities [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Stock price (dollars per share)	$ 16.22	$ 14.87
Volatility	18.00%	18.00%
Assumed annual stock dividend	5.00%	5.00%
Assumed annual cash dividend (dollars per share)	$ 1.60	$ 1.60
Convertible trading price	117.94%	109.00%
Implied credit spread	8.50%	10.50%
Minimum [Member] | Derivative Financial Instruments, Liabilities [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Implied credit spread	8.00%	10.00%
Maximum [Member] | Derivative Financial Instruments, Liabilities [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Implied credit spread	9.00%	11.00%