9. Long-Term Debt

Changes in long-term debt, excluding current portion, (in millions) were as follows:



	For the Three
	Months Ended
		March 31,
		2018
Balance as of beginning-of-year		$	4,894
Senior notes issued:
4.00% notes, due 2023			150
3.80% notes, due 2028			500
4.35% notes, due 2048			450
Early extinguishment of 8.75% notes, due 2019			(287	)
Unamortized premiums (discount)			4
Unamortized debt issuance costs			(9	)
Fair value hedge-interest rate swap agreements			(54	)
Balance as of end-of-period		$	5,648

Details underlying the recognition of a gain (loss) on the early extinguishment of debt (in millions) reported within interest expense on our Consolidated Statements of Comprehensive Income (Loss) were as follows:



	For the Three
	Months Ended
		March 31,
		2018
Principal balance outstanding prior to payoff (1)		$	287
Unamortized debt issuance costs and
discounts prior to payoff			(1	)
Amount paid to retire debt			(309	)
Gain (loss) on early extinguishment of debt, pre-tax		$	(23	)

⁽¹⁾

During the first quarter of 2018, we repurchased $287 million of our 8.75% senior notes due 2019.