Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accumulated depreciation, buildings	$ 292,049	$ 282,804
Accumulated depreciation, machinery and equipment	$ 668,950	$ 620,113
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	148,410,422	150,081,474
Common stock, shares outstanding (in shares)	148,410,422	150,081,474