Marketable Securities - Unrestricted (Unrealized Losses On Investments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Total Number in Loss Position	5
Less than twelve months - fair values	$ 997
Less than twelve months - unrealized losses	(16)
Twelve months or greater - fair values	25,025
Twelve months or greater - unrealized losses	(369)
Total Fair Value	26,022
Total Unrealized Losses	(385)
Mutual Funds [Member]
Total Number in Loss Position	1
Less than twelve months - fair values	0
Less than twelve months - unrealized losses	0
Twelve months or greater - fair values	21,753
Twelve months or greater - unrealized losses	(334)
Total Fair Value	21,753
Total Unrealized Losses	(334)
Corporate Bonds [Member]
Total Number in Loss Position	4
Less than twelve months - fair values	997
Less than twelve months - unrealized losses	(16)
Twelve months or greater - fair values	3,272
Twelve months or greater - unrealized losses	(35)
Total Fair Value	4,269
Total Unrealized Losses	$ (51)