Represents the amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

No definition available.

Fair Value Of Financial Instruments (Details) (USD $)	6 Months Ended
Fair Value Of Financial Instruments (Details) (USD $)	Jun. 30, 2012 item	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value of Financial Instruments
Cash and cash equivalents, cost	$ 3,970,000	$ 40,025,000	$ 4,420,000	$ 14,340,000
Cash and cash equivalents, fair value	3,970,000	40,025,000
Estimated fair values of financial instruments
Unrealized Gains	16,000	6,000
Unrealized Losses	(17,000)	(5,000)
Fair value of available-for-sale securities with unrealized losses	28,200,000
Number of maturity groups	2
Investments by rolling maturity, Cost
Due within 1 year	26,340,000
Due in 1-2 years	18,630,000
Total	44,970,000	17,949,000
Investments by fiscal year maturity, Cost
Due within 1 year		9,412,000
Due in 1-2 years		8,537,000
Total	44,970,000	17,949,000
Investments by rolling maturity, Unrealized Gains
Due within 1 year	11,000
Due in 1-2 years	5,000
Total	16,000	6,000
Investments by fiscal year maturity, Unrealized Gains
Due within 1 year		3,000
Due in 1-2 years		3,000
Total	16,000	6,000
Investments by rolling maturity, Unrealized Losses
Due within 1 year	(8,000)
Due in 1-2 years	(9,000)
Total	(17,000)	(5,000)
Investments by fiscal year maturity, Unrealized Losses
Due within 1 year		(2,000)
Due in 1-2 years		(3,000)
Total	(17,000)	(5,000)
Investments by rolling maturity, Fair Value
Due within 1 year	26,343,000
Due in 1-2 years	18,626,000
Total	44,969,000	17,950,000
Investments by fiscal year maturity, Fair Value
Due within 1 year		9,413,000
Due in 1-2 years		8,537,000
Total	44,969,000	17,950,000
Short-term investments
Estimated fair values of financial instruments
Cost	26,340,000	9,412,000
Unrealized Gains	11,000	3,000
Unrealized Losses	(8,000)	(2,000)
Fair Value	26,343,000	9,413,000
Investments by rolling maturity, Unrealized Gains
Total	11,000	3,000
Investments by fiscal year maturity, Unrealized Gains
Total	11,000	3,000
Investments by rolling maturity, Unrealized Losses
Total	(8,000)	(2,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(8,000)	(2,000)
Short-term investments \| U.S. government debt securities
Estimated fair values of financial instruments
Cost	8,130,000	4,834,000
Unrealized Gains	1,000	2,000
Unrealized Losses	(3,000)
Fair Value	8,128,000	4,836,000
Investments by rolling maturity, Unrealized Gains
Total	1,000	2,000
Investments by fiscal year maturity, Unrealized Gains
Total	1,000	2,000
Investments by rolling maturity, Unrealized Losses
Total	(3,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(3,000)
Short-term investments \| Corporate notes and commercial paper
Estimated fair values of financial instruments
Cost	14,143,000
Unrealized Gains	7,000
Unrealized Losses	(4,000)
Fair Value	14,146,000
Investments by rolling maturity, Unrealized Gains
Total	7,000
Investments by fiscal year maturity, Unrealized Gains
Total	7,000
Investments by rolling maturity, Unrealized Losses
Total	(4,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(4,000)
Short-term investments \| Corporate notes
Estimated fair values of financial instruments
Cost		4,578,000
Unrealized Gains		1,000
Unrealized Losses		(2,000)
Fair Value		4,577,000
Investments by rolling maturity, Unrealized Gains
Total		1,000
Investments by fiscal year maturity, Unrealized Gains
Total		1,000
Investments by rolling maturity, Unrealized Losses
Total		(2,000)
Investments by fiscal year maturity, Unrealized Losses
Total		(2,000)
Short-term investments \| Certificates of deposit
Estimated fair values of financial instruments
Cost	4,067,000
Unrealized Gains	3,000
Unrealized Losses	(1,000)
Fair Value	4,069,000
Investments by rolling maturity, Unrealized Gains
Total	3,000
Investments by fiscal year maturity, Unrealized Gains
Total	3,000
Investments by rolling maturity, Unrealized Losses
Total	(1,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(1,000)
Long-term investments
Estimated fair values of financial instruments
Cost	18,630,000	8,537,000
Unrealized Gains	5,000	3,000
Unrealized Losses	(9,000)	(3,000)
Fair Value	18,626,000	8,537,000
Investments by rolling maturity, Unrealized Gains
Total	5,000	3,000
Investments by fiscal year maturity, Unrealized Gains
Total	5,000	3,000
Investments by rolling maturity, Unrealized Losses
Total	(9,000)	(3,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(9,000)	(3,000)
Long-term investments \| U.S. government debt securities
Estimated fair values of financial instruments
Cost	11,641,000	5,721,000
Unrealized Gains	2,000	1,000
Unrealized Losses	(4,000)	(1,000)
Fair Value	11,639,000	5,721,000
Investments by rolling maturity, Unrealized Gains
Total	2,000	1,000
Investments by fiscal year maturity, Unrealized Gains
Total	2,000	1,000
Investments by rolling maturity, Unrealized Losses
Total	(4,000)	(1,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(4,000)	(1,000)
Long-term investments \| Corporate notes
Estimated fair values of financial instruments
Cost	6,268,000	2,816,000
Unrealized Gains	3,000	2,000
Unrealized Losses	(5,000)	(2,000)
Fair Value	6,266,000	2,816,000
Investments by rolling maturity, Unrealized Gains
Total	3,000	2,000
Investments by fiscal year maturity, Unrealized Gains
Total	3,000	2,000
Investments by rolling maturity, Unrealized Losses
Total	(5,000)	(2,000)
Investments by fiscal year maturity, Unrealized Losses
Total	(5,000)	(2,000)
Long-term investments \| Certificates of deposit
Estimated fair values of financial instruments
Cost	721,000
Fair Value	$ 721,000