Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2016

Schedule of cash and cash equivalents and other investments reconciliation from adjusted cost to fair value

Our cash and cash equivalents and other investments consist of the following:



	June 30, 2016
	Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
	(in millions)
Cash	$	112	$	—	$	—	$	112
Cash equivalents:
U.S. and Canadian government obligations	1,873		—		—		1,873
Other debt securities	23		—		—		23
Total cash and cash equivalents	$	2,008	$	—	$	—	$	2,008
Restricted cash	7		—		—		7
Nonqualified employee benefit trusts	18		1		—		19



	December 31, 2015
	Cost Basis		Unrealized Gains		Unrealized Losses		Fair Value
	(in millions)
Cash	$	71	$	—	$	—	$	71
Cash equivalents:
U.S. and Canadian government obligations	190		—		—		190
Other debt securities	25		—		—		25
Total cash and cash equivalents	$	286	$	—	$	—	$	286
Restricted cash	23		—		—		23
Nonqualified employee benefit trusts	18		1		—		19

Schedule of assets and liabilities measured at fair value on a recurring basis

The following tables present assets and liabilities included in our consolidated balance sheets as of June 30, 2016 and December 31, 2015 that are recognized at fair value on a recurring basis, and indicate the fair value hierarchy utilized to determine such fair value:



	June 30, 2016
	Total Fair Value			Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
	(in millions)
Cash equivalents	$	1,896		$	1,896	$	—		$	—
Restricted cash	7			7		—			—
Derivative assets	14			—		14			—
Nonqualified employee benefit trusts	19			19		—			—
Derivative liabilities	(36		)	—		(36		)	—



	December 31, 2015
	Total Fair Value			Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
	(in millions)
Cash equivalents	$	215		$	215	$	—		$	—
Restricted cash	23			23		—			—
Nonqualified employee benefit trusts	19			19		—			—
Derivative liabilities	(211		)	—		(211		)	—

Schedule of carrying amounts and estimated fair values of financial instruments

The carrying amount and estimated fair value of our long-term debt is as follows:



	June 30, 2016				December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(in millions)
Long-term debt	$	5,540	$	5,751	$	5,537	$	5,456