CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	250,000	250,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	264,500,000	264,500,000
Common stock, shares outstanding (in shares)	229,300,000	230,100,000
Treasury stock, shares (in shares)	35,200,000	34,400,000