FAIR VALUE

Financial Assets

The following table summarizes our fair value measurements at September 30, 2017 and December 31, 2016, respectively, for financial assets measured at fair value on a recurring basis:



	Fair Value Measurements Using
	Fair Value		Quoted Prices in Active Markets (Level 1)		Other Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
	(in millions)
September 30, 2017
Cash equivalents	$	9,368	$	9,368	$	—	$	—
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	814		—		814		—
Mortgage-backed securities	1,409		—		1,409		—
Tax-exempt municipal securities	3,469		—		3,469		—
Mortgage-backed securities:
Residential	7		—		7		—
Commercial	400		—		400		—
Asset-backed securities	140		—		140		—
Corporate debt securities	5,099		—		5,098		1
Total debt securities	11,338		—		11,337		1
Total invested assets	$	20,706	$	9,368	$	11,337	$	1

December 31, 2016
Cash equivalents	$	3,654	$	3,654	$	—	$	—
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	786		—		786		—
Mortgage-backed securities	1,637		—		1,637		—
Tax-exempt municipal securities	3,305		—		3,302		3
Mortgage-backed securities:
Residential	9		—		9		—
Commercial	304		—		304		—
Asset-backed securities	160		—		160		—
Corporate debt securities	3,597		—		3,593		4
Total debt securities	9,798		—		9,791		7
Total invested assets	$	13,452	$	3,654	$	9,791	$	7

There were no material transfers between Level 1 and Level 2 during the three and nine months ended September 30, 2017 or 2016.

Our Level 3 assets had a fair value of $1 million at September 30, 2017, less than 0.01% of our total invested assets. During the three and nine months ended September 30, 2017 and 2016, the changes in the fair value of the assets measured using significant unobservable inputs (Level 3) were comprised of the following:



	For the three months ended September 30,
	2017									2016
	Private Placements			Auction Rate Securities			Total			Private Placements		Auction Rate Securities			Total
	(in millions)
Beginning balance at July 1	$	4		$	—		$	4		$	6	$	3		$	9
Sales	(3		)	—			(3		)	—		—			—
Balance at September 30	$	1		$	—		$	1		$	6	$	3		$	9



	For the nine months ended September 30,
	2017									2016
	Private Placements			Auction Rate Securities			Total			Private Placements		Auction Rate Securities			Total
	(in millions)
Beginning balance at January 1	$	4		$	3		$	7		$	6	$	5		$	11
Sales	(3		)	—			(3		)	—		—			—
Settlements	—			(3		)	(3		)	—		(2		)	(2		)
Balance at September 30	$	1		$	—		$	1		$	6	$	3		$	9

Financial Liabilities

Our debt is recorded at carrying value in our consolidated balance sheets. The carrying value of our senior notes debt outstanding, including the current portion, net of unamortized debt issuance costs, was $4,780 million at September 30, 2017 and $3,792 million at December 31, 2016. The fair value of our senior notes debt, including the current portion, was $5,185 million at September 30, 2017 and $4,004 million at December 31, 2016. The fair value of our long-term debt is determined based on Level 2 inputs, including quoted market prices for the same or similar debt, or if no quoted market prices are available, on the current prices estimated to be available to us for debt with similar terms and remaining maturities.

Due to the short-term nature, carrying value approximates fair value for our commercial paper borrowings. There were outstanding commercial paper borrowings of $150 million as of September 30, 2017 and $300 million as of December 31, 2016.

Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis

As disclosed in Note 3, we completed the acquisition of certain health and wellness related businesses during 2017 and 2016. The values of net tangible assets acquired and the resulting goodwill and other intangible assets were recorded at fair value using Level 3 inputs. The majority of the tangible assets acquired and liabilities assumed were recorded at their carrying values as of the respective dates of acquisition, as their carrying values approximated their fair values due to their short-term nature. The fair values of goodwill and other intangible assets acquired in these acquisitions were internally estimated primarily based on the income approach. The income approach estimates fair value based on the present value of the cash flows that the assets are expected to generate in the future. We developed internal estimates for the expected cash flows and discount rates used in the present value calculations. Other than assets acquired and liabilities assumed in these acquisitions, there were no material assets or liabilities measured at fair value on a nonrecurring basis during 2017 or 2016.