Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Available-for-sale Securities

The following tables summarize the Company's investments in marketable securities:

	Amortized		Unrealized					Fair
As of December 31, 2016	Cost Basis		Gains		Losses			Value
Corporate bonds	$	1,076,964	$	630	$	(4,743	)	$	1,072,851
U.S. government and government agency obligations	132,923		58		(641		)	132,340
Municipal bonds	7,663		1		(20		)	7,644
Commercial paper	63,074		1		—			63,075
Certificates of deposit	42,612		—		—			42,612
Equity securities	57,251		5,551		(13,583		)	49,219
	$	1,380,487	$	6,241	$	(18,987	)	$	1,367,741

As of December 31, 2015
Corporate bonds	$	770,092	$	156	$	(2,565	)	$	767,683
U.S. government and government agency obligations	51,402		—		(193		)	51,209
Municipal bonds	17,930		5		(11		)	17,924
Equity securities	17,005		14,462		—			31,467
	$	856,429	$	14,623	$	(2,769	)	$	868,283

Marketable Securities, Based on Contractual Maturity Dates

The fair values of debt security investments by contractual maturity consist of the following:

	As of December 31,
	2016		2015
Maturities within one year	$	503,482	$	236,121
Maturities after one year through five years	815,040		600,695
	$	1,318,522	$	836,816

Fair Value and Unrealized Losses of Marketable Securities

The following table shows the fair value of the Company's marketable securities that have unrealized losses and that are deemed to be only temporarily impaired, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position.

	Less than 12 Months					12 Months or Greater					Total
As of December 31, 2016	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate bonds	$	759,222	$	(4,685	)	$	36,407	$	(58	)	$	795,629	$	(4,743	)
U.S. government and government agency obligations	81,170		(641		)	—		—			81,170		(641		)
Municipal bonds	7,141		(20		)	—		—			7,141		(20		)
Equity securities	36,417		(13,583		)	—		—			36,417		(13,583		)
	$	883,950	$	(18,929	)	$	36,407	$	(58	)	$	920,357	$	(18,987	)
As of December 31, 2015
Corporate bonds	$	668,199	$	(2,473	)	$	23,749	$	(92	)	$	691,948	$	(2,565	)
U.S. government and government agency obligations	51,215		(193		)	—		—			51,215		(193		)
Municipal bonds	11,917		(11		)	—		—			11,917		(11		)
	$	731,331	$	(2,677	)	$	23,749	$	(92	)	$	755,080	$	(2,769	)