Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.06	$ 0.06
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	259,328,613	280,281,321
Common stock, shares outstanding (in shares)	259,328,613	280,281,321