Investments And Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2011

Investments And Marketable Securities [Abstract]

Changes In Unrealized Gains And Losses On Available-For-Sale Securities

	Year Ended December 31,
	2011		2010		2009
Changes in unrealized gains and losses on available-for- sale securities, net of tax, recorded in accumulated other comprehensive income (loss)	$	(385)	$	(406)	$	737

Aggregate Market Value And Unrealized Losses Of Investments

Unrealized Loss < 12 months						Unrealized Loss > 12 months
	Number of investments	Aggregate Market Value		Unrealized     Losses			Number of investments	Aggregate Market Value		Unrealized     Losses
Government securities	5	$	4,599	$	(3)		6	$	6,708	$	(4)
State and municipal bonds	16		24,556		(7)		11		18,612		(36)
Corporate Securities	35		31,461		(855)		53		17,057		(532)
Total	56	$	60,616	$	(865)		70	$	42,377	$	(572)

As of December 31, 2010, the number, aggregate market value and unrealized losses (in thousands) of investments with market values that were less than amortized cost were:

	Unrealized Loss < 12 months					Unrealized Loss > 12 months
	Number of investments	Aggregate Market Value		Unrealized     Losses		Number of investments	Aggregate Market Value		Unrealized     Losses
Government securities	0	$	0	$	0	1	$	610	$	(6)
State and municipal bonds	10		17,707		(6)	13		20,461		(457)
Corporate Securities	3		4,029		(8)	12		13,850		(478)
Total	13	$	21,736	$	(14)	26	$	34,921	$	(941)

Schedule Of Realized Gains On The Sales Of Available-For-Sale Securities

	Year Ended December 31,
	2011		2010		2009
Proceeds	$	303,801	$	102,485	$	56,020
Realized gains		388		458		260
Realized losses		(306)		(198)		(219)
Net realized losses included in other comprehensive income (loss) as of the end of the prior year		159		(264)		(26)