Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
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)	175,000,000	175,000,000
Common stock, shares issued (in shares)	101,766,468	98,924,501
Common stock, shares outstanding (in shares)	88,103,566	85,261,664
Treasury cost, shares (in shares)	13,663,194	13,663,194