CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	280,000,000	280,000,000
Common stock, shares issued (in shares)	148,263,534	148,107,038
Common stock, shares outstanding (in shares)	139,998,722	140,103,841
Treasury stock shares (in shares)	8,264,812	8,003,197