Summary of Significant Accounting Policies (Held-to-Maturity Securities) (Details) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Corporate Debt Securities [Member]	Dec. 31, 2011 Corporate Debt Securities [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Current			$ 1,267
Held To Maturity Gross Unrecognized Gains Current
Held To Maturity Gross Unrecognized Losses Current
Held To Maturity Aggregate Fair Value Current			1,267
Held-to-maturity, Noncurrent	761	1,000	261
Held To Maturity Gross Unrecognized Gains Noncurrent
Held To Maturity Gross Unrecognized Losses Noncurrent
Held To Maturity Aggregate Fair Value Noncurrent			$ 261
Investment Maturity Period					1 year	2 years