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	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value of Financial Instruments
Cash and cash equivalents, cost	$ 3,110	$ 4,364	$ 2,529	$ 40,025
Cash and cash equivalents, fair value	3,110	4,364
Estimated fair values of financial instruments
Unrealized Gains	3	23
Unrealized Losses	(13)	(10)
Short-term investments.
Estimated fair values of financial instruments
Cost	20,442	32,183
Unrealized Gains	3	14
Unrealized Losses	(6)	(5)
Fair Value	20,439	32,192
Short-term investments. \| U.S. government-sponsored enterprise bonds
Estimated fair values of financial instruments
Cost	1,250	6,543
Unrealized Losses		(1)
Fair Value	1,250	6,542
Short-term investments. \| Municipal Bonds
Estimated fair values of financial instruments
Cost	841	13,401
Unrealized Gains		11
Fair Value	841	13,412
Short-term investments. \| Corporate notes
Estimated fair values of financial instruments
Cost	15,921	7,245
Unrealized Gains	2	2
Unrealized Losses	(6)	(2)
Fair Value	15,917	7,245
Short-term investments. \| Certificates of deposit
Estimated fair values of financial instruments
Cost	2,430	4,994
Unrealized Gains	1	1
Unrealized Losses		(2)
Fair Value	2,431	4,993
Long-term investments
Estimated fair values of financial instruments
Cost	2,252	13,922
Unrealized Gains		9
Unrealized Losses	(7)	(5)
Fair Value	2,245	13,926
Long-term investments \| U.S. government-sponsored enterprise bonds
Estimated fair values of financial instruments
Cost	1,000	2,752
Unrealized Losses	(2)
Fair Value	998	2,752
Long-term investments \| Municipal Bonds
Estimated fair values of financial instruments
Cost		264
Fair Value		264
Long-term investments \| Corporate notes
Estimated fair values of financial instruments
Cost	1,252	9,466
Unrealized Gains		9
Unrealized Losses	(5)	(1)
Fair Value	1,247	9,474
Long-term investments \| Certificates of deposit
Estimated fair values of financial instruments
Cost		1,440
Unrealized Losses		(4)
Fair Value		$ 1,436