3. Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Fair Value Assets Measured on Recurring Basis

As of December 31, 2015	Level 1		Level 2		Total
Bank deposits	$	440,809	$	—	$	440,809
Money market funds	1,732,449		—		1,732,449
Cash and cash equivalents	2,173,258		—		2,173,258
Corporate debt securities	1,401,453		—		1,401,453
Commercial paper	249,888		—		249,888
Short term investments	1,651,341		—		1,651,341
Total	$	3,824,599	$	—	$	3,824,599
As of December 31, 2014	Level 1		Level 2		Total
Bank deposits	$	972,891	$	—	$	972,891
Money market funds	1,565,867		—		1,565,867
Cash and cash equivalents	2,538,758		—		2,538,758
Corporate debt securities	6,799,702		—		6,799,702
Commercial paper	599,934		—		599,934
Short term investments	7,399,636		—		7,399,636
Total	$	9,938,394	$	—	$	9,938,394