Investments and Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [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 June 30, 2013
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	$	219,533	$	219,533	$	—	$	—
Certificates of deposit	2,234		—		2,234		—
Bonds	7,577		7,577		—		—
Investment securities available for sale							—
Equity securities	86,691		79,947		6,744		—
Fixed income securities
U.S. Government securities	10,094		—		10,094		—
Corporate securities	30,031		—		30,031		—
U.S. mortgage backed securities	589		—		589		—
Commercial mortgage-backed securities	5,886		—		5,886		—
U.S. asset backed securities	850		—		850		—
Total fixed income securities	47,450		—		47,450		—
Warrants	806		—		—		806
Total	$	364,291	$	307,057	$	56,428	$	806
Liabilities:
Fair value of derivatives embedded within convertible debt	166,629		—		—		166,629
Total	$	166,629	$	—	$	—	$	166,629

	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:
Equity securities	69,984		69,107		877		—
Warrants	769		—		—		769
Total	$	452,017	$	448,131	$	3,117	$	769
Liabilities:
Fair value of derivatives embedded within convertible debt	172,128		—		—		172,128
Total	$	172,128	$	—	$	—	$	172,128

Unobservable inputs related to the valuations of the Level 3 assets and liabilities

The unobservable inputs related to the valuations of the Level 3 assets and liabilities are as follows at June 30, 2013:

	Quantitative Information about Level 3 Fair Value Measurements
	Fair Value at
	June 30, 2013		Valuation Technique	Unobservable Input	Range (Actual)
Warrants	$	806	Option model	Stock price	$	1.54
				Exercise price	$	1.68
				Term (in years)	4.4
				Volatility	95.19		%
				Dividend rate	—
				Risk-free return	0.64		%
Fair value of derivatives embedded within convertible debt	$	166,629	Discounted cash flow	Assumed annual stock dividend	5		%
				Assumed annual cash dividend	$	1.60
				Stock price	$	16.22
				Convertible trading price	117.94		%
				Volatility	18		%
				Implied credit spread	8% - 9% (8.5%)

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	109.00		%
				Volatility	18		%
				Implied credit spread	10% - 11% (10.5%)