Summary Of Significant Accounting Policies (Schedule Of Investments In Money Market Funds Table) (Details) (BlackRock Liquidity Temporary Fund - Institutional [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2012 Taxable Money Market Funds [Member]
Investment Holdings [Line Items]
Cost	$ 42,273	$ 58,620
Fair Value	$ 42,273	$ 58,620