Cash Equivalents And Restricted Cash And Securities (Summary Of Cash Equivalents And Restricted Cash And Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	$ 46,935	$ 35,075	$ 46,935	$ 35,075	$ 37,588	$ 33,375
Unrealized Holding Gains	0	$ 0	0	$ 0
Cash [Member] | Restricted Cash And Securities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis					5,000
Unrealized Holding Gains
Estimated Market Value					5,000
Money Market Funds [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	753		753		830
Money Market Funds [Member] | Cash Equivalents [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	715		715		549
Unrealized Holding Gains
Estimated Market Value	715		715		549
Money Market Funds [Member] | Restricted Cash And Securities [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cost Basis	753		753		830
Unrealized Holding Gains
Estimated Market Value	$ 753		$ 753		$ 830