Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2017

Investments, All Other Investments [Abstract]

Summary of Carrying Amounts and Estimated Fair Values of Other Financial Instruments

The following table summarizes the carrying amounts and estimated fair values of our other financial instruments at June 30, 2017:

	Carrying Amount		Fair Value
	(Dollars in thousands)
Assets:
Cash and cash equivalents	$	142,083	$	142,083
Natural gas swap agreements	103		103
Liabilities:
Bank debt	$	1,489,971	$	1,489,971
5% Senior Notes	280,000		283,903
5½% Senior Notes	300,000		309,558
4¾% Senior Notes	300,000		307,533
3¼% Senior Notes	742,105		762,238