Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	63,769,000	62,830,000
Common stock, shares outstanding	63,769,000	62,552,000