CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Class A [Member]	Common Class B [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]
Opening Balance SHARES at Dec. 31, 2015		32,480,551	7,197,532
Compensation expense related to granting of restricted stock awards SHARES		1,095,759	0
Issuance of common stock related to an incentive plan SHARES		31,933	0
Exercise of stock options SHARES		134,238	0
Purchase of vested employee restricted stock units SHARES		(232,297)	0
Ending Balance SHARES at Dec. 31, 2016		33,510,184	7,197,532
Opening Balance VALUE at Dec. 31, 2015	$ 361,450	$ 325	$ 72	$ 611,754	$ (250,701)
Net income (loss)	38,065	0	0	0	38,065
Compensation expense related to granting of restricted stock awards VALUE	6,539	11	0	6,528	0
Issuance of common stock related to an incentive plan VALUE	379	0	0	379	0
Purchase of vested employee restricted stock units	(2,268)	(2)	0	(2,266)	0
Payments of dividends VALUE	(8,666)	0	0	(8,666)	0
Exercise of stock options VALUE	265	1	0	264	0
Preferred stock dividend	(1,788)	0	0	(1,788)	0
AdjustmentsToAdditionalPaidInCapitalOther	(602)	0	0	(602)	0
Ending Balance VALUE at Dec. 31, 2016	$ 393,374	$ 335	$ 72	605,603	(212,636)
Compensation expense related to granting of stock options SHARES	0
Compensation expense related to granting of restricted stock awards SHARES		26,193	0
Issuance of common stock related to an incentive plan SHARES		14,873	0
Exercise of stock options SHARES	4,000	4,000	0
Purchase of vested employee restricted stock units SHARES		(157,739)	0
Ending Balance SHARES at Mar. 31, 2017		33,397,511	7,197,532
Net income (loss)	$ (9,331)	$ 0	$ 0	0	(9,331)
Compensation expense related to granting of restricted stock awards VALUE	1,593	0	0	1,593	0
Issuance of common stock related to an incentive plan VALUE	181	0	0	181	0
Purchase of vested employee restricted stock units	(2,436)	(1)	0	(2,435)	0
Payments of dividends VALUE	(3,014)	0	0	(3,014)	0
Exercise of stock options VALUE	5	0	0	5	0
Preferred stock dividend	(550)	0	0	(550)	0
AdjustmentsToAdditionalPaidInCapitalOther	(56)	0	0	(56)	0
Ending Balance VALUE at Mar. 31, 2017	384,878	334	72	601,861	(217,389)
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 5,112	$ 0	$ 0	$ 534	$ 4,578