Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 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:

	December 31, 2016				December 31, 2015
	Cost		Fair Value		Cost		Fair Value
Cash and cash equivalents:
Cash and overnight deposits	$	406,787	406,787		445,582		445,582
Corporate commercial paper	507,777		507,889		302,433		302,480
Time deposits	59,871		59,871		59,781		59,781
Total cash and cash equivalents	974,435		974,547		807,796		807,843
Short-term investments:
Time deposits	35		35		40		40
Total	$	974,470	$	974,582	$	807,836	$	807,883