Note 14 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2020	Feb. 28, 2020	Dec. 31, 2019	Sep. 30, 2019
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01		$ 0.01
ATM Program [Member]
Common Stock, Par or Stated Value Per Share (in dollars per share)				$ 0.01
Sales of Stock Maximum Sales Price				$ 500.0
Share Repurchase Program [Member]
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.01
Stock Repurchase Program, Authorized Amount		$ 300.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 224.9