Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (USD per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	15,000,000.0	15,000,000.0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.10	$ 0.10
Common stock, share authorized (in shares)	150,000,000.0	150,000,000.0
Common stock, shares issued (in shares)	76,800,000	77,300,000
Common stock, shares outstanding (in shares)	76,800,000	77,300,000
Treasury stock, shares (in shares)	2,100,000	800,000