CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($)	Total	Common Class A [Member]	Common Class B [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]
Opening Balance SHARES at Dec. 31, 2013		31,308,194	7,197,532
Conversion of Class B common stock to Class A common stock SHARES		0	0
Compensation expense related to granting of restricted stock awards SHARES		638,102	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES		57,500	0
Purchase of vested employee restricted stock units SHARES	(142,000)	(141,502)	0
Ending Balance SHARES at Dec. 31, 2014		31,862,294	7,197,532
Opening Balance VALUE at Dec. 31, 2013	$ 298,393,000	$ 313,000	$ 72,000	$ 604,721,000	$ (306,713,000)
Net income (loss)	26,823,000				26,823,000
Compensation expense related to granting of restricted stock awards VALUE	5,232,000	7,000	0	5,225,000	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0
Purchase of vested employee restricted stock units	(1,514,000)	(1,000)	0	(1,513,000)	0
Forfeitures of dividend equivalents VALUE	5,000	0	0	0	5,000
Realization of tax benefit for dividend equivalent payments VALUE	0	0	0	0	0
Exercise of stock options VALUE	82,000	0	0	82,000	0
Preferred stock dividend	0
Net unrealized gain (loss) on investments VALUE		0
Net unrealized gain (loss) on derivatives VALUE	0		0	0	0
Ending Balance VALUE at Dec. 31, 2014	$ 329,021,000	$ 319,000	$ 72,000	608,515,000	(279,885,000)
Conversion of Class B common stock to Class A common stock SHARES		0	0
Compensation expense related to granting of restricted stock awards SHARES		738,195	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES		11,750	0
Purchase of vested employee restricted stock units SHARES	(132,000)	(131,688)	0
Ending Balance SHARES at Dec. 31, 2015		32,480,551	7,197,532
Net income (loss)	$ 29,184,000				29,184,000
Compensation expense related to granting of restricted stock awards VALUE	5,524,000	$ 7,000	$ 0	5,517,000	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0
Purchase of vested employee restricted stock units	(1,562,000)	(1,000)	0	(1,561,000)	0
Forfeitures of dividend equivalents VALUE	0	0	0	0	0
Realization of tax benefit for dividend equivalent payments VALUE	0	0	0	0	0
Exercise of stock options VALUE	35,000	0	0	35,000	0
Preferred stock dividend	(752,000)			(752,000)
Net unrealized gain (loss) on derivatives VALUE		0	0		0
Ending Balance VALUE at Dec. 31, 2015	$ 361,450,000	$ 325,000	$ 72,000	611,754,000	(250,701,000)
Conversion of Class B common stock to Class A common stock SHARES		0	0
Compensation expense related to granting of stock options SHARES	0
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	134,238	0
Purchase of vested employee restricted stock units SHARES	(232,000)	(232,297)	0
Ending Balance SHARES at Dec. 31, 2016		33,510,184	7,197,532
Net income (loss)	$ 38,065,000				38,065,000
Compensation expense related to granting of restricted stock awards VALUE	6,539,000	$ 11,000	$ 0	6,528,000	0
Issuance of common stock related to an incentive plan VALUE	379,000	0	0	379,000	0
Common stock repurchase VALUE	0	0	0	0	0
Purchase of vested employee restricted stock units	(2,268,000)	(2,000)	0	(2,266,000)	0
Payments of dividends VALUE	(8,666,000)	0	0	(8,666,000)	0
Forfeitures of dividend equivalents VALUE	0	0	0	0	0
Exercise of stock options VALUE	265,000	1,000	0	264,000	0
Preferred stock dividend	(1,788,000)	0	0	(1,788,000)	0
Net unrealized gain (loss) on investments VALUE	0	0	0	0	0
Net unrealized gain (loss) on derivatives VALUE	0	0	0	0	0
Ending Balance VALUE at Dec. 31, 2016	393,374,000	335,000	72,000	605,603,000	(212,636,000)
AdjustmentsToAdditionalPaidInCapitalOther	$ (602,000)	$ 0	$ 0	$ (602,000)	$ 0