Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2012

Investments, Debt and Equity Securities [Abstract]

Available-for-sale securities

The following is a summary of the Company’s available-for-sale securities as of December 31, 2012:

	Available-for-sale securities
	Amortized Cost Basis		Unrealized Gain		Fair Value
U.S. Treasury Bonds	$	40,104	$	159	$	40,263
U.S. Agency Bonds	50,401		205		50,606
Corporate Bonds	135,922		602		136,524
Total available-for-sale securities	$	226,427	$	966	$	227,393

Schedule of available-for-sale securities reconciliation

The following table provides the activity for the marketable securities during the year ended December 31, 2012:

	Amortized Cost Basis			Unrealized Gain			Fair Value
Marketable securities as of January 1, 2012	$	—		$	—		$	—
Face value of marketable securities acquired	235,000			—			235,000
Premiums and discounts on purchase of marketable securities, net of acquisition costs	8,444			—			8,444
Amortization on marketable securities	(713		)	—			(713		)
Sales of securities and realized gain	(16,304		)	(141		)	(16,445		)
Increase in fair value of marketable securities	—			1,107			1,107
Marketable securities as of December 31, 2012	$	226,427		$	966		$	227,393

Investments classified by contractual maturity date

The scheduled maturities of the Company’s marketable securities as of December 31, 2012 are as follows:

	Available-for-sale securities
	Amortized Cost		Estimated Fair Value
Due within one year	$	5,001	$	5,001
Due after one year through five years	184,410		185,385
Due after five years through ten years	37,016		37,007
Due after ten years	—		—
Total	$	226,427	$	227,393