Consolidated Balance Sheets (Parentheticals) - $ / shares	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 0.01			$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000			10,000,000
Preferred stock, shares issued (in shares)	0			0
Preferred stock, shares outstanding (in shares)	0			0
Common stock, par value (in dollars per share)	$ 0.01			$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000			1,000,000,000
Common stock, shares outstanding (in shares)	60,206,977			60,094,623
Convertible Stock
Common stock, par value (in dollars per share)	$ 0.01			$ 0.01
Common stock, shares authorized (in shares)	50,000			50,000
Common stock, shares issued (in shares)	50,000			50,000
Common stock, shares outstanding (in shares)	50,000	50,000	50,000	50,000	50,000	50,000	50,000	50,000