Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Fair value of Cash and Cash Equivalents by Balance Sheet Grouping

Cash, cash equivalents and short-term investments consist of the following:

	March 31, 2016			December 31, 2015
	Cost		Fair Value	Cost	Fair Value
Cash and Cash Equivalents:
Cash and overnight deposits	$	509,685	509,685	445,582	445,582
Corporate commercial paper	438,536		438,613	302,433	302,480
Time deposits	65,696		65,696	59,781	59,781
Total cash and cash equivalents	1,013,917		1,013,994	807,796	807,843
Short-Term Investments:
Time deposits	71		71	40	40
Total	$	1,013,988	1,014,065	807,836	807,883