2. Cash and Available for Sale Securities

The following table summarizes the Company's cash and available-for-sale securities' amortized cost and estimated fair value by significant investment category as of December 31, 2012 and 2011 (in thousands):

	Amortized Cost and Estimated Fair Value
	December 31,
	2012		2011
Cash and cash equivalents:
Cash	$	1,203	$	7,205
Cash equivalents
Money market mutual funds		249		1,045
Certificates of deposit		500		3,100
Commercial paper		4,400		6,600
Total cash equivalents		5,149		10,745
Total cash and cash equivalents		6,352		17,950
Short-term investments:
Corporate bonds		1,258		2,031
Certificates of deposit		3,301		3,278
Commercial paper		4,947		1,500
Total short-term investments		9,506		6,809
Total cash, and cash equivalents, and short-term investments	$	15,858	$	24,759

Realized gains and realized losses were not significant for either of the years ended December 31, 2012 or 2011. As of December 31, 2012 and 2011, there were no significant unrealized losses on investments. The cost of all securities sold is based on the specific identification method.

The contractual maturities of cash equivalents and short-term investments at December 31, 2012 and 2011 were less than one year. There were no long-term investments at December 31, 2012 and 2011.

The Company typically invests in highly-rated securities, and its policy generally limits the amount of credit exposure to any one issuer. When evaluating the investments for other-than-temporary impairment, the Company reviews such factors as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer, and the Company's intent to sell, or whether it is more likely than not it will be required to sell, the investment before recovery of the investment's amortized cost basis. During the years ended December 31, 2012 and 2011, the Company did not recognize any impairment charges on outstanding investments. As of December 31, 2012, the Company does not consider any of its investments to be other-than-temporarily impaired.