Marketable Securities	9 Months Ended
Sep. 30, 2013
Marketable Securities [Abstract]
Marketable Securities	Marketable Securities Marketable securities consist primarily of corporate bonds and certificates of deposit with maturities greater than three months and up to ten years at the time of purchase as well as marketable equity securities. These securities, which are classified as available-for-sale, are carried at fair value, with unrealized gains and losses, net of any tax effect, reported in stockholders’ equity as accumulated other comprehensive income (loss). For the three and nine months ended September 30, 2013, gains of $263 and $136 were reclassified from accumulated other comprehensive income and recognized in the income statement in other income. These securities are classified as current and non-current marketable securities based upon their maturities. Amortization of premiums and discounts is included in interest income. For the three and nine months ended September 30, 2013, the amortization of bond premiums totals $161 and $521, respectively, compared to $182 and $710 for the comparable periods in 2012. The values of these securities may fluctuate as a result of changes in equity values, market interest rates and credit risk.

Marketable Securities

Marketable securities consist primarily of corporate bonds and certificates of deposit with maturities greater than three months and up to ten years at the time of purchase as well as marketable equity securities. These securities, which are classified as available-for-sale, are carried at fair value, with unrealized gains and losses, net of any tax effect, reported in stockholders’ equity as accumulated other comprehensive income (loss). For the three and nine months ended September 30, 2013, gains of $263 and $136 were reclassified from accumulated other comprehensive income and recognized in the income statement in other income. These securities are classified as current and non-current marketable securities based upon their maturities. Amortization of premiums and discounts is included in interest income. For the three and nine months ended September 30, 2013, the amortization of bond premiums totals $161 and $521, respectively, compared to $182 and $710 for the comparable periods in 2012. The values of these securities may fluctuate as a result of changes in equity values, market interest rates and credit risk.