Marketable Securities (Scheduled Maturities Of Available-For-Sale Debt Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule Of Marketable Securities [Line Items]
Due within one year, fair value	$ 806	$ 8,703
Due after one year through five years, fair value	1,111	3,856
Due after five years through 10 years, fair value	295
Total, fair value	2,212	12,559
Due within one year, amortized cost	805	8,699
Due after one year through five years, amortized cost	1,094	3,853
Due after five years through 10 years, amortized cost	283
Total, amortized cost	$ 2,182	$ 12,552