Note 12 - Selected Quarterly Financial Data (Unaudited) (Details) - Selected Quarterly Financial Data (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Selected Quarterly Financial Data [Abstract]
Revenue (less agency commissions)	$ 177,886	$ 131,702	$ 107,249	$ 91,297	$ 95,556	$ 88,288	$ 84,285	$ 78,169	$ 508,134	$ 346,298	$ 404,831
Operating income	72,021	41,156	23,186	17,410	23,288	24,220	21,312	15,060	153,773	83,880	153,441
Net income	$ 31,253	$ 13,940	$ 1,591	$ 1,277	$ 5,201	$ 7,073	$ 5,144	$ 870	$ 48,061	$ 18,288	$ 28,129
Basic net income per share (in Dollars per share)	$ 0.54	$ 0.24	$ 0.03	$ 0.02	$ 0.09	$ 0.12	$ 0.09	$ 0.02	$ 0.83	$ 0.32	$ 0.42
Diluted net income per share (in Dollars per share)	$ 0.53	$ 0.24	$ 0.03	$ 0.02	$ 0.09	$ 0.12	$ 0.09	$ 0.02	$ 0.82	$ 0.32	$ 0.42