FAIR VALUE (Tables)

9 Months Ended

Sep. 30, 2017

Marketable securities

FAIR VALUE

Schedule of carrying amounts and fair values of assets and liabilities

The amortized cost and fair values of our marketable securities are as follows (dollars in thousands):

	As of September 30, 2017				As of December 31, 2016
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Marketable securities	$	861	$	1,071	$	987	$	1,103

Long-term debt

FAIR VALUE

Schedule of carrying amounts and fair values of assets and liabilities

The principal amounts and fair values of our debt are as follows (dollars in thousands):

	As of September 30, 2017				As of December 31, 2016
	Principal		Estimated		Principal		Estimated
	Amount		Fair Value		Amount		Fair Value
Total debt	$	3,156,583	$	3,509,168	$	3,259,721	$	3,543,640