Investments and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]

Company's recurring financial assets and liabilities subject to fair value measurements

The Company's recurring financial assets and liabilities subject to fair value measurements are as follows:

	Fair Value Measurements as of December 31, 2012
Description	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds	$	372,718	$	372,718	$	—	$	—
Certificates of deposit	2,240		—		2,240		—
Bonds	6,306		6,306		—		—
Investment securities available for sale	69,984		69,107		877		—
Warrants (1)	769		—		—		769
Total	$	452,017	$	448,131	$	3,117	$	769
Liabilities:
Fair value of derivatives embedded within convertible debt	$	172,128	$	—	$	—	$	172,128

(1) Warrants include 1,000,000 of LTS Warrants received on November 4, 2011 which were carried at $717 as of December 31, 2012 and are included in "Other assets". The Company recognized a loss of $1,174 for the year ended December 31, 2012 related to the change in fair value of the Warrants.

	Fair Value Measurements as of December 31, 2011
Description	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds	$	194,259	$	194,259	$	—	$	—
Certificates of deposit	2,206		—		2,206		—
Bonds	4,573		4,573		—		—
Investment securities available for sale	76,486		70,884		5,602		—
Warrants (1)	1,962		—		—		1,962
Total	$	279,486	$	269,716	$	7,808	$	1,962
Liabilities:
Fair value of derivatives embedded within convertible debt	$	133,500	$	—	$	—	$	133,500

(1) Warrants include 1,000,000 of LTS Warrants received on November 4, 2011 which were carried at $1,890 as of December 31, 2011 and are included in "Other assets". The Company recognized income of $690 for the year ended December 31, 2011 related to the change in fair value from receipt. (See Note 14.)

Fair value inputs, assets and liabilities, quantitative information

The unobservable inputs related to the valuations of the Level 3 assets and liabilities are as follows at December 31, 2012:

	Quantitative Information about Level 3 Fair Value Measurements
	Fair Value at
	December 31, 2012		Valuation Technique	Unobservable Input	Range (Actual)
Warrants	$	769	Option model	Stock price	$	1.40
				Exercise price	$	1.68
				Term (in years)	3.8
				Volatility	76.87		%
				Dividend rate	—
				Risk-free return	0.50		%
Fair value of derivatives embedded within convertible debt	172,128		Discounted cash flow	Assumed annual stock dividend	5		%
				Assumed annual cash dividend	$	1.60
				Stock price	$	14.87
				Convertible trading price	109.0		%
				Volatility	18.00		%
				Implied credit spread	10.00% - 11.00% (10.50%)

The unobservable inputs related to the valuations of the Level 3 assets and liabilities are as follows at December 31, 2011:

	Quantitative Information about Level 3 Fair Value Measurements
	Fair Value at
	December 31, 2011		Valuation Technique	Unobservable Input	Range (Actual)
Warrants	$	1,962	Option model	Stock price	$	2.48
				Exercise price	$	1.68
				Term (in years)	4.9
				Volatility	94.12		%
				Dividend rate	—
				Risk-free return	0.83		%
Fair value of derivatives embedded within convertible debt	133,500		Discounted cash flow	Assumed annual stock dividend	5		%
				Assumed annual cash dividend	$	1.60
				Yield to worst call on the Company's senior secured notes	9.33		%
				Average spread of unsecured debt	1.49		%
				Average spread of subordinated debt	1.89		%
				Discount rate	12% - 13% (12.5%)