Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

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, 2013			December 31, 2012
	Cost		Fair Value	Cost	Fair Value
Cash and cash equivalents:
Cash and overnight deposits	$	590,317	590,317	458,169	458,169
Corporate commercial paper	629,923		629,990	642,884	642,886
Time deposits	27,412		27,412	159,789	159,789
Total cash and cash equivalents	1,247,652		1,247,719	1,260,842	1,260,844
Short-term investments:
Corporate commercial paper	26,296		26,321	—	—
Time deposits	41		41	139	139
Total short-term investments	26,337		26,362	139	139
Total	$	1,273,989	1,274,081	1,260,981	1,260,983