Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value Disclosures [Abstract]

Schedule of Fair Value - Assets Measured on Recurring Basis

The following tables set forth by level within the fair value hierarchy the Company's assets and liabilities that were recorded at fair value as of September 30, 2011 and December 31, 2010 (in thousands). As required by the guidance for fair value measurements, financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Thus, assets and liabilities categorized as Level 3 may be measured at fair value using inputs that are observable (Levels 1 and 2) and unobservable (Level 3). Management's assessment of the significance of a particular input to the fair value measurement requires judgment, which may affect the valuation of assets and liabilities and their placement within the fair value hierarchy levels.

	At Fair Value as of September 30, 2011
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	—	$	251,175	$	—	$	251,175
Commercial paper	—		197,617		—		197,617
U.S. government or government agency securities	—		310,315		—		310,315
Total	$	—	$	759,107	$	—	$	759,107

	At Fair Value as of December 31, 2010
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	—	$	168,831	$	—	$	168,831
Commercial paper	—		17,494		—		17,494
U.S. government or government agency securities	—		108,364		—		108,364
Total	$	—	$	294,689	$	—	$	294,689

Available-for-sale Securities

Available-for-sale securities were comprised as follows as of September 30, 2011 and December 31, 2010 (in thousands):

	As of September 30, 2011
	Cost		Fair Value
Money market funds	$	251,175	$	251,175
Commercial paper	197,616		197,617
U.S. government or government agency securities	310,316		310,315
	$	759,107	$	759,107

	As of December 31, 2010
	Cost		Fair Value
Money market funds	$	168,831	$	168,831
Commercial paper	17,494		17,494
U.S. government or government agency securities	108,364		108,364
	$	294,689	$	294,689

Schedule of Fair Value - Assets Measured on a Nonrecurring Basis

The tables below summarize the non-financial assets that were measured and recorded at fair value on a non-recurring basis as of September 30, 2011 and December 31, 2010 and the losses recorded during the three and nine months ended September 30, 2011 and the year ending December 31, 2010 on those assets (in thousands):

	At Fair Value as of September 30, 2011
	Level 1		Level 2		Level 3		Losses
Assets:
Wireless licenses	$	—	$	—	$	9,115	$	377
Total	$	—	$	—	$	9,115	$	377

	At Fair Value as of December 31, 2010
	Level 1		Level 2		Level 3		Losses
Assets:
Goodwill	$	—	$	—	$	—	$	430,101
Property and equipment	—		—		—		46,460
Wireless licenses	—		—		7,496		766
Total	$	—	$	—	$	7,496	$	477,327