Long-Term Investments	12 Months Ended
Dec. 31, 2017
Investments All Other Investments [Abstract]
Long-Term Investments	3. Long-Term Investments As of December 31, 2017, the Company held an auction rate security with a par value of $2.5 million. This auction rate security has not experienced a successful auction since the liquidity issues experienced in the global credit and capital markets in 2008. As a result the security is classified as a long-term investment as it is scheduled to mature in 2038. The security was rated A- by Standard and Poor’s as of December 31, 2017. The security continues to pay interest according to its stated terms. The valuation of the Company’s auction rate security is subject to uncertainties that are difficult to predict. The fair value of the security is estimated utilizing a discounted cash flow analysis. The key drivers of the valuation model include the expected term, collateral underlying the security investment, the creditworthiness of the counterparty, the timing of expected future cash flows, discount rates, liquidity and the expected holding period. The security was also compared, when possible, to other observable market data for securities with similar characteristics. As of December 31, 2017, the inputs used in the Company’s discounted cash flow analysis assumed an interest rate of 3.92%, an estimated redemption period of five years and a discount rate of 1.0%. Based on the valuation of the security, the Company has recognized cumulative losses of $0.4 million as of December 31, 2017, none of which were realized during the year ended December 31, 2017. The losses, when recognized, are included in investment and other income. The market value of the security has partially recovered. Included in other comprehensive (loss) income are unrealized gains (losses) of $108,000, $(6,000) and $48,000 for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, the Company had recorded cumulative unrealized gains of $0.4 million. The resulting carrying value of the auction rate security at December 31, 2017, was $2.2 million. Any future decline in market value may result in additional losses being recognized.

3. Long-Term Investments

As of December 31, 2017, the Company held an auction rate security with a par value of $2.5 million. This auction rate security has not experienced a successful auction since the liquidity issues experienced in the global credit and capital markets in 2008. As a result the security is classified as a long-term investment as it is scheduled to mature in 2038. The security was rated A- by Standard and Poor’s as of December 31, 2017. The security continues to pay interest according to its stated terms.

The valuation of the Company’s auction rate security is subject to uncertainties that are difficult to predict. The fair value of the security is estimated utilizing a discounted cash flow analysis. The key drivers of the valuation model include the expected term, collateral underlying the security investment, the creditworthiness of the counterparty, the timing of expected future cash flows, discount rates, liquidity and the expected holding period. The security was also compared, when possible, to other observable market data for securities with similar characteristics. As of December 31, 2017, the inputs used in the Company’s discounted cash flow analysis assumed an interest rate of 3.92%, an estimated redemption period of five years and a discount rate of 1.0%. Based on the valuation of the security, the Company has recognized cumulative losses of $0.4 million as of December 31, 2017, none of which were realized during the year ended December 31, 2017. The losses, when recognized, are included in investment and other income. The market value of the security has partially recovered. Included in other comprehensive (loss) income are unrealized gains (losses) of $108,000, $(6,000) and $48,000 for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, the Company had recorded cumulative unrealized gains of $0.4 million. The resulting carrying value of the auction rate security at December 31, 2017, was $2.2 million. Any future decline in market value may result in additional losses being recognized.