Investments (Tables)

3 Months Ended

Mar. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Aggregate Fair Value, Amortized Cost Basis and Net Unrealized Gains and Losses Included in Accumulated Other Comprehensive Income (Loss) of Available-for-Sale Investments

The following table sets forth the aggregate fair value, amortized cost basis and net unrealized gains and losses included in accumulated other comprehensive income (loss) of our available-for-sale investments as of the dates indicated:

	As of:
	March 31, 2013						December 31, 2012						March 31, 2012
	Aggregate Fair Value		Amortized Cost		Net Unrealized Gains (Losses)		Aggregate Fair Value		Amortized Cost		Net Unrealized Gains (Losses)		Aggregate Fair Value		Amortized Cost		Net Unrealized Gains (Losses)
Available-for-Sale Investments:
Government obligations	$	0	$	0	$	0	$	0	$	0	$	0	$	80,445	$	80,446	($	1	)
Government agency obligations		0		0		0		0		0		0		17,022		17,022		0
Corporate obligations		0		0		0		0		0		0		17,339		17,340		(1	)
	$	0	$	0	$	0	$	0	$	0	$	0	$	114,806	$	114,808	($	2	)

Components of Investment Income Included in Interest Income

The following table sets forth the components of investment income included in Interest income in our Condensed Consolidated Statements of Income in the periods indicated:

	Three Months Ended March 31,
	2013		2012
Interest income on investments	$	34	$	141
Realized net gains on the sale of investments		0		14
Total investment income	$	34	$	155