Fair value of financial instruments (Tables)

9 Months Ended

Sep. 30, 2018

Fair value of financial instruments.

Schedule of fair value of assets measured on recurring basis

The following fair value hierarchy table presents information about each major category of our financial assets measured at fair value on a recurring basis (in thousands):

	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		September 30, 2018
Cash and cash equivalents	$	1,112,179	$	—	$	—	$	1,112,179
Debt securities (corporate and government)		—		263,134		—		263,134
Long term investments (Note 9)		121,381		—		—		121,381
Total assets	$	1,233,560	$	263,134	$	—	$	1,496,694

	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Cash and cash equivalents	$	899,509	$	—	$	—	$	899,509
Debt securities (corporate and government)		—		270,136		—		270,136
Long term investment (Note 9)		134,356		—		—		134,356
Total assets	$	1,033,865	$	270,136	$	—	$	1,304,001

Schedule of fair value of liabilities measured on recurring basis

The following fair value hierarchy table presents information about each major category of our financial liabilities measured at fair value on a recurring basis as (in thousands):

	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		September 30, 2018
Contingent consideration	$	—	$	—	$	286,000	$	286,000
Total liabilities	$	—	$	—	$	286,000	$	286,000

	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Contingent consideration	$	—	$	—	$	287,000	$	287,000
Total liabilities	$	—	$	—	$	287,000	$	287,000

Schedule of rollforward of Level 3 liabilities

The following is a rollforward of our Level 3 liabilities (in thousands):

	Level 3
Balance at January 1, 2018	$	287,000
Contingent consideration earned during the period but not yet paid		(13,023)
Payments made during the period		(6,685)
Change in fair value of contingent consideration		18,708
Balance at September 30, 2018	$	286,000

Summary of marketable securities portfolio

The following is a summary of our marketable security portfolio.

			Net		Net
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gains		Losses		Fair Value
	(in thousands)
September 30, 2018
Debt securities (corporate and government)	$	264,589	$	—	$	(1,455)	$	263,134
December 31, 2017
Debt securities (corporate and government)	$	271,401	$	—	$	(1,265)	$	270,136