Cash Equivalents And Restricted Cash And Securities (Summary Of Cash Equivalents And Marketable Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Cash [Member] \| Restricted Cash And Securities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	$ 5,000	$ 5,000
Unrealized Holding Gains (Losses)
Estimated Market Value	$ 5,000	$ 5,000
Money Market Funds [Member] \| Cash Equivalents [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	$ 549	$ 18,213
Unrealized Holding Gains (Losses)
Estimated Market Value	$ 549	$ 18,213
Money Market Funds [Member] \| Restricted Cash And Securities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	$ 830	$ 884
Unrealized Holding Gains (Losses)
Estimated Market Value	$ 830	$ 884

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

Name:	us-gaap_MoneyMarketFundsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant