Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 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:

	June 30, 2016			December 31, 2015
	Cost		Fair Value	Cost	Fair Value
Cash and Cash Equivalents:
Cash and overnight deposits	$	451,445	451,445	445,582	445,582
Corporate commercial paper	478,146		478,183	302,433	302,480
Time deposits	50,673		50,673	59,781	59,781
Total cash and cash equivalents	980,264		980,301	807,796	807,843
Short-Term Investments:
Time deposits	71		71	40	40
Total	$	980,335	980,372	807,836	807,883