Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fees receivable, allowances	$ 12,700	$ 7,400
Preferred stock par value (in Dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock par value (in Dollars per share)	$ 0.0005	$ 0.0005
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	163,602,067	156,234,415
Treasury stock, Shares	72,779,205	73,583,172