Fair Value Measurements

Fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of December 31, 2017 and January 1, 2017 are as follows (in millions):



	December 31, 2017								January 1, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Money market funds (cash equivalent)	$	957	$	—	$	—	$	957	$	386	$	—	$	—	$	386
Debt securities in government-sponsored entities	—		67		—		67		—		34		—		34
Corporate debt securities	—		421		—		421		—		476		—		476
U.S. Treasury securities	432		—		—		432		314		—		—		314
Deferred compensation plan assets	—		35		—		35		—		31		—		31
Total assets measured at fair value	$	1,389	$	523	$	—	$	1,912	$	700	$	541	$	—	$	1,241
Liabilities:
Acquisition-related contingent consideration liabilities	$	—	$	—	$	—	$	—	$	—	$	—	$	4	$	4
Deferred compensation liability	—		33		—		33		—		29		—		29
Total liabilities measured at fair value	$	—	$	33	$	—	$	33	$	—	$	29	$	4	$	33

We hold available-for-sale securities that consist of highly-liquid, investment-grade debt securities. We consider information provided by our investment accounting and reporting service provider in the measurement of fair value of our debt securities. The investment service provider provides valuation information from an industry-recognized valuation service. Such valuations may be based on trade prices in active markets for identical assets or liabilities (Level 1 inputs) or valuation models using inputs that are observable either directly or indirectly (Level 2 inputs), such as quoted prices for similar assets or liabilities, yield curve, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, broker and dealer quotes, as well as other relevant economic measures. Our deferred compensation plan assets consist primarily of investments in life insurance contracts carried at cash surrender value, which reflects the net asset value of the underlying publicly traded mutual funds. We perform control procedures to corroborate the fair value of our holdings, including comparing valuations obtained from our investment service provider to valuations reported by our asset custodians, validating pricing sources and models, and reviewing key model inputs, if necessary.

The fair value of any contingent consideration liabilities is reassessed on a quarterly basis using the income approach. Assumptions used to estimate the acquisition date fair value of the contingent consideration include discount rates ranging from 4% to 6% and the probability of achieving certain milestones. The fair value measurement of the contingent consideration is based on significant inputs not observed in the market (Level 3 inputs). Significant inputs used in the measurement include probabilities of achieving the remaining milestones and the discount rates, which depend on the milestone risk profiles. The changes in fair value of the contingent consideration during the years ended December 31, 2017, January 1, 2017, and January 3, 2016 were due to changes in the estimated payments and discounting periods.

Changes in estimated fair value of contingent consideration liabilities from December 28, 2014 through December 31, 2017 are as follows (in millions):



	Contingent Consideration Liability (Level 3 Measurement)
Balance as of December 28, 2014	$	44
Change in estimated fair value, recorded in selling, general and administrative expenses	(6		)
Cash payments	(3		)
Balance as of January 3, 2016	35
Additional liability recorded as a result of a current period acquisition	5
Change in estimated fair value, recorded in selling, general and administrative expenses	(1		)
Cash payments	(35		)
Balance as of January 1, 2017	4
Change in estimated fair value, recorded in selling, general and administrative expenses	(1		)
Cash payments	(3		)
Balance as of December 31, 2017	$	—