Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2017

Fair Value Disclosures [Abstract]

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

Cash and cash equivalents consist of the following:

	March 31, 2017			December 31, 2016
	Cost		Fair Value	Cost	Fair Value
Cash and Cash Equivalents:
Cash and overnight deposits	$	424,861	424,861	406,787	406,787
Corporate commercial paper	669,046		669,287	507,777	507,889
Time deposits	62,136		62,136	59,871	59,871
Total cash and cash equivalents	$	1,156,043	1,156,284	974,435	974,547