Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Fair Value of Financial Instruments
Cash and cash equivalents, cost	$ 7,020	$ 3,110	$ 2,113	$ 4,364
Cash and cash equivalents, fair value	7,020	3,110
Estimated fair values of financial instruments
Unrealized Gains	6	3
Unrealized Losses	(10)	(13)
Short-term investments.
Estimated fair values of financial instruments
Cost	26,068	20,442
Unrealized Gains	4	3
Unrealized Losses	(6)	(6)
Fair Value	26,066	20,439
Short-term investments. \| U.S. government-sponsored enterprise bonds
Estimated fair values of financial instruments
Cost	8,710	1,250
Unrealized Losses	(3)
Fair Value	8,707	1,250
Short-term investments. \| Municipal Bonds
Estimated fair values of financial instruments
Cost	3,071	841
Unrealized Gains	1
Fair Value	3,072	841
Short-term investments. \| Corporate notes
Estimated fair values of financial instruments
Cost	10,835	15,921
Unrealized Gains	2	2
Unrealized Losses	(3)	(6)
Fair Value	10,834	15,917
Short-term investments. \| Certificates of deposit
Estimated fair values of financial instruments
Cost	2,953	2,430
Unrealized Gains	1	1
Fair Value	2,954	2,431
Short-term investments. \| Commercial Paper
Estimated fair values of financial instruments
Cost	499
Fair Value	499
Long-term investments
Estimated fair values of financial instruments
Cost	7,599	2,252
Unrealized Gains	2
Unrealized Losses	(4)	(7)
Fair Value	7,597	2,245
Long-term investments \| U.S. government-sponsored enterprise bonds
Estimated fair values of financial instruments
Cost	1,001	1,000
Unrealized Losses	(1)	(2)
Fair Value	1,000	998
Long-term investments \| Corporate notes
Estimated fair values of financial instruments
Cost	6,598	1,252
Unrealized Gains	2
Unrealized Losses	(3)	(5)
Fair Value	$ 6,597	$ 1,247