Long-Term Debt (Tables)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Long-Term Debt

	June 30,			December 31,			June 30,
	2015			2014			2014
	(Dollars in Thousands)
6.6% Senior Notes, due 2018	$	299,243		$	299,123		$	299,006
7% Debentures, due 2025		124,516			124,500			124,485
6.25% Senior Notes, due 2037		228,208			228,184			228,165
4.25 % Senior Notes, due 2024		395,511			395,309			—
Floating Rate Notes, due 2017, interest rate of 1.38% and      1.33% at June 30, 2015 and December 31, 2014, respectively		299,108			298,869			—
Term Loan Facility, due 2018, interest rate of 1.69% at June 30,      2015; 1.67% at December 31, 2014; and 1.65% at June 30, 2014		230,167			236,258			242,350
Revolving Facility, interest rate of 1.40% at June 30, 2014		—			—			40,000
Trade Receivable Facility, interest rate of 0.88% and 0.75% at      June 30, 3015 and 2014, respectively		80,000			—			150,000
Other notes		1,248			3,152			795
Total debt		1,658,001			1,585,395			1,084,801
Less: Current maturities		(15,966	)		(14,336	)		(12,404	)
Long-term debt	$	1,642,035		$	1,571,059		$	1,072,397