Investments	12 Months Ended
Dec. 31, 2015
Investments [Abstract]
Investments	3. Investments As of December 31, 2015, the Company’s investments, consisting of U.S. treasury notes with maturities up to approximately two years, were classified as available-for-sale. As of December 31, 2014, the Company’s investments consisted of U.S. treasury notes and CDARS, certificates of deposit placed through an account registry service, with maturities up to approximately two years, and were classified as held-to-maturity. Fair market value of U.S. treasury notes is measured on a recurring basis based on Level 1 inputs and fair market value of CDARS is measured on a recurring basis based on Level 2 inputs (level inputs are described in Note 1 under “Fair Value Measurements”). The Company designates the appropriate classification of its investments at the time of purchase based upon the intended holding period. During the year ended December 31, 2015, the Company transferred the classification of its investments from held-to-maturity to available-for-sale due to anticipated liquidity needs related to increased repurchases of shares of the Company’s common stock. The carrying value of held-to-maturity securities transferred to available-for-sale during the year ended December 31, 2015 was $1,040,850 and the fair market value of those securities was determined to be $1,038,138, resulting in an unrealized holding loss of $2,712. As a result, the Company recorded $2,468 ($1,522, net of tax) of unrealized holding losses in other comprehensive income (loss), and an other-than-temporary impairment charge of $244 in interest and other income (expense), in the consolidated statement of income and comprehensive income. The Company determined its investments approximated fair value as of December 31, 2014, and no impairment charges were recognized on the Company’s investments for the years ended December 31, 2014 and 2013. The Company has elected to fund certain deferred compensation obligations through a rabbi trust, the assets of which are designated as trading securities, as described further in Note 7. “Employee Benefit Plans.”

Investments

12 Months Ended

Dec. 31, 2015

3. Investments

As of December 31, 2015, the Company’s investments, consisting of U.S. treasury notes with maturities up to approximately two years, were classified as available-for-sale. As of December 31, 2014, the Company’s investments consisted of U.S. treasury notes and CDARS, certificates of deposit placed through an account registry service, with maturities up to approximately two years, and were classified as held-to-maturity. Fair market value of U.S. treasury notes is measured on a recurring basis based on Level 1 inputs and fair market value of CDARS is measured on a recurring basis based on Level 2 inputs (level inputs are described in Note 1 under “Fair Value Measurements”).

The Company designates the appropriate classification of its investments at the time of purchase based upon the intended holding period. During the year ended December 31, 2015, the Company transferred the classification of its investments from held-to-maturity to available-for-sale due to anticipated liquidity needs related to increased repurchases of shares of the Company’s common stock. The carrying value of held-to-maturity securities transferred to available-for-sale during the year ended December 31, 2015 was $1,040,850 and the fair market value of those securities was determined to be $1,038,138, resulting in an unrealized holding loss of $2,712. As a result, the Company recorded $2,468 ($1,522, net of tax) of unrealized holding losses in other comprehensive income (loss), and an other-than-temporary impairment charge of $244 in interest and other income (expense), in the consolidated statement of income and comprehensive income. The Company determined its investments approximated fair value as of December 31, 2014, and no impairment charges were recognized on the Company’s investments for the years ended December 31, 2014 and 2013.

The Company has elected to fund certain deferred compensation obligations through a rabbi trust, the assets of which are designated as trading securities, as described further in Note 7. “Employee Benefit Plans.”