Cash, Cash Equivalents and Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2011

Cash, Cash Equivalents and Marketable Securities [Abstract]

Summary of investments in cash, cash equivalents and marketable securities

The following table summarizes the Company's investments in cash equivalents and marketable securities held by investment managers and overnight investments:

	June 30,			December 31,
	2011			2010
	(in thousands)
Overnight Holdings
Money market funds (cash equivalents)	$	82,413		$	157,680
Investment Holdings
Money market funds (cash equivalents)		87,952			72,258
Marketable securities		37,598			43,367
		207,963			273,305
Cash held in demand accounts		105,672			31,295
Outstanding checks		(10,846	)		(26,404	)
Total cash, cash equivalents and marketable securities	$	302,789		$	278,196
Cash and cash equivalents	$	265,191		$	234,829
Marketable securities		37,598			43,367
	$	302,789		$	278,196

Summary of fair value measurements of financial assets

The following table summarizes the levels of fair value measurements of the Company's financial assets:

	Fair Value Measurements
	(in thousands)
	June 30,
	2011		Level 1		Level 2		Level 3
Money market funds	$	170,365	$	170,365	$	-	$	-
Municipal bonds		37,598		-		37,598		-
Total	$	207,963	$	170,365	$	37,598	$	-

	Fair Value Measurements
	(in thousands)
	December 31,
	2010		Level 1		Level 2		Level 3
Money market funds	$	229,938	$	229,938	$	-	$	-
Municipal bonds		43,367		-		43,367		-
Total	$	273,305	$	229,938	$	43,367	$	-

Contractual maturities of marketable secuities

As of June 30, 2011, the contractual maturities of the Company's marketable securities were as follows:

	Amortized Cost		Estimated Fair Value
	(in thousands)
Less than one year	$	20,369	$	20,395
One to five years		17,128		17,203
Total	$	37,497	$	37,598

Summary of available-for-sale securities

The following table summarizes the Company's available-for-sale marketable securities as of June 30, 2011 and December 31, 2010:

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
			(in thousands)
June 30, 2011:
Municipal bonds	$	37,497	$	110	$	(9	)	$	37,598
December 31, 2010:
Municipal bonds	$	43,330	$	63	$	(26	)	$	43,367