Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Disclosures [Abstract]

Schedule of assets measured at fair value on a recurring basis

The Company’s assets that are measured at fair value on a recurring basis, at December 31, 2012 and 2011, consist of the following:

			Fair Value Measurements at Reporting Date Using
At December 31, 2012	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Unrestricted
Available-for-sale marketable securities:
U.S. government and government agency obligations	$	328,146			$	328,146
Municipal bonds	17,510				17,510
Equity security	3,393		$	3,393
	349,049		3,393		345,656
Restricted
Available-for-sale marketable securities:
U.S. government obligations	5,909				5,909
	$	354,958	$	3,393	$	351,565
At December 31, 2011
Unrestricted
Available-for-sale marketable securities:
U.S. government and government agency obligations	$	284,819			$	284,819
U.S. government guaranteed corporate bonds	15,317				15,317
U.S. government guaranteed collateralized mortgage obligations	623				623
Municipal bonds	15,326				15,326
Mortgage-backed securities	115				115
Equity security	3,019		$	3,019
	319,219		3,019		316,200
Restricted
Available-for-sale marketable securities:
U.S. government obligations	5,940				5,940
	$	325,159	$	3,019	$	322,140