Fair Value

Financial assets and liabilities measured at fair value on a recurring basis at December 31, 2018 and 2017 were (in millions):



2018	Level 1		Level 2		Level 3		Total
Assets:
Cash and cash equivalents	$	3,652.4					$	3,652.4
Short-term investments	5.5						5.5
Marketable equity investments	1.5						1.5
Liabilities:
Interest rate and foreign currency derivatives			$	52.9			$	52.9
Contingent purchase price obligations					$	146.5	146.5
2017
Assets:
Cash and cash equivalents	$	3,796.0					$	3,796.0
Short-term investments	0.4						0.4
Marketable equity investments	1.4						1.4
Foreign currency derivatives			$	1.0			1.0
Liabilities:
Interest rate and foreign currency derivatives			$	39.5			$	39.5
Contingent purchase price obligations					$	215.6	215.6

Changes in contingent purchase price obligations for the years ended December 31, 2018 and 2017 were (in millions):



	2018			2017
January 1	$	215.6		$	386.1
Acquisitions	85.8			31.9
Revaluation and interest	(30.1		)	(27.4		)
Payments	(100.3		)	(187.0		)
Foreign currency translation	(24.5		)	12.0
December 31	$	146.5		$	215.6

The carrying amount and fair value of our financial assets and liabilities at December 31, 2018 and 2017 were (in millions):



	2018				2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Assets:
Cash and cash equivalents	$	3,652.4	$	3,652.4	$	3,796.0	$	3,796.0
Short-term investments	5.5		5.5		0.4		0.4
Marketable equity investments	1.5		1.5		1.4		1.4
Non-marketable equity investments	11.8		11.8		14.4		14.4
Foreign currency derivatives	—		—		1.0		1.0
Liabilities:
Short-term debt	$	8.1	$	8.1	$	11.8	$	11.8
Interest rate and foreign currency derivatives	52.9		52.9		39.5		39.5
Contingent purchase price obligations	146.5		146.5		215.6		215.6
Long-term debt, including current portion	4,883.7		4,821.3		4,912.9		5,056.9

The estimated fair value of the foreign currency and interest rate derivative instruments is determined using model-derived valuations, taking into consideration foreign currency rates for the foreign currency derivatives and readily observable inputs for LIBOR interest rates and yield curves to derive the present value of the future cash flows for the interest rate derivatives and counterparty credit risk for each. The estimated fair value of the contingent purchase price obligations is calculated in accordance with the terms of each acquisition agreement and is discounted. The fair value of long-term debt is based on quoted market prices.