Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fees receivable, allowance for credit loss	$ 10,000	$ 8,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0005	$ 0.0005
Common stock, authorized (in shares)	250,000,000	250,000,000
Common stock, issued (in shares)	163,602,067	163,602,067
Treasury stock (in shares)	74,759,985	74,444,288