Debt and Other Financing Arrangements (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of Debt and Other Financing Arrangements

(in thousands) December 31,
	2015		2014
Industrial revenue bonds:
0.17% to 0.42%, variable, due from 2015 to 2040	$	1,010,600	$	1,026,935
Notes, 5.75%, due 2017		600,000		600,000
Notes, 5.85%, due 2018		500,000		500,000
Notes, 4.125%, due 2022		600,000		600,000
Notes, 4.0%, due 2023		500,000		500,000
Notes, 6.40%, due 2037		650,000		650,000
Notes, 5.20%, due 2043		500,000		500,000
		4,360,600		4,376,935
Less current maturities		—		(16,335	)
Total long-term debt due after one year	$	4,360,600	$	4,360,600