Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Additional Paid in Capital	Retained Earnings (Deficit)	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Class A	Class A Common Stock	Class B	Class B Common Stock
Beginning Balance at Dec. 31, 2014	$ 851,653	$ 834,538	$ 35,144	$ (18,751)	$ 679		$ 36		$ 7
Beginning Balance, shares at Dec. 31, 2014							34,469,650		6,940,048
Net income (loss)	2,502		2,502
Exchange of B shares to A shares							$ 1		$ (1)
Exchange of B shares to A shares, shares							2,366,406		(2,366,406)
Stock-based compensation, RSU and warrant expense	3,874	3,874
Treasury stock purchases	(802)			(802)
Treasury stock purchases, shares							(30,000)
Exercise of stock options and warrants	873	873
Exercise of stock options and warrants, shares							43,501
Other	(20)	(20)
Other comprehensive income (loss)	(601)				(601)
Ending Balance at Jun. 30, 2015	857,479	839,265	37,646	(19,553)	78		$ 37		$ 6
Ending Balance, shares at Jun. 30, 2015							36,849,557		4,573,642
Beginning Balance at Dec. 31, 2015	876,109	850,609	88,535	(53,635)	(9,443)		$ 39		$ 4
Beginning Balance, shares at Dec. 31, 2015						37,126,571	37,126,571	3,733,882	3,733,882
Net income (loss)	45,956		45,956
Exchange of B shares to A shares							$ 1		$ (1)
Exchange of B shares to A shares, shares							834,862		(834,862)
Stock-based compensation, RSU and warrant expense	2,238	2,238
Treasury stock purchases	(20,264)			(20,264)
Treasury stock purchases, shares							(617,550)
Exercise of stock options and warrants	4,889	4,889
Exercise of stock options and warrants, shares							293,891
Restricted stock units (RSUs), shares							1,119
Other	(15)	(15)
Other comprehensive income (loss)	14,259				14,259
Ending Balance at Jun. 30, 2016	$ 923,172	$ 857,721	$ 134,491	$ (73,899)	$ 4,816		$ 40		$ 3
Ending Balance, shares at Jun. 30, 2016						37,638,893	37,638,893	2,899,020	2,899,020