CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, except Share data	Total	Common Class A Member	Common Class B Member	Additional Paid In Capital Member	Retained Earnings Member	Accumulated Other Comprehensive Income (Loss) Member
Opening Balance VALUE at Dec. 31, 2010	$ 170,667	$ 307	$ 74	$ 592,643	$ (415,080)	$ (7,277)
Opening Balance SHARES at Dec. 31, 2010		30,700,568	7,367,532
Conversion of Class B common stock to Class A common stock SHARES		170,000	(170,000)
Compensation expense related to granting of stock options SHARES		0	0
Compensation expense related to granting of restricted stock units SHARES		416,906	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES		53,625	0
Purchase of vested employee restricted stock units SHARES		(297,098)	0
Net income (loss)	68,510	0	0	0	68,510	0
Conversion of Class B common stock to Class A common stock VALUE	0	2	(2)	0	0	0
Compensation expense related to granting of stock options VALUE	462	0	0	462	0	0
Compensation expense related to granting of restricted stock units VALUE	7,209	4	0	7,205	0	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0	0
Purchase of vested employee restricted stock units VALUE	(3,057)	(3)	0	(3,054)	0	0
Forfeitures of dividend equivalents VALUE	5	0	0	0	5	0
Realization of tax benefit for dividend equivalent payments VALUE	0	0	0	0	0	0
Exercise of stock options VALUE	71	0	0	71	0	0
Net unrealized gain (loss) on derivatives VALUE	7,277	0	0	0	0	7,277
Ending Balance VALUE at Dec. 31, 2011	251,144	310	72	597,327	(346,565)	0
Ending Balance SHARES at Dec. 31, 2011		31,044,001	7,197,532
Conversion of Class B common stock to Class A common stock SHARES		0	0
Compensation expense related to granting of stock options SHARES	0	0	0
Compensation expense related to granting of restricted stock units SHARES		281,791	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES	(40,400)	40,400	0
Purchase of vested employee restricted stock units SHARES		(37,876)	0
Net income (loss)	(1,049)	0	0	0	(1,049)	0
Conversion of Class B common stock to Class A common stock VALUE	0	0	0	0	0	0
Compensation expense related to granting of stock options VALUE	79	0	0	79	0	0
Compensation expense related to granting of restricted stock units VALUE	1,318	3	0	1,315	0	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0	0
Purchase of vested employee restricted stock units VALUE	(301)	0	0	(301)	0	0
Payments of dividends VALUE	0	0	0	0	0	0
Forfeitures of dividend equivalents VALUE	9	0	0	0	9	0
Exercise of stock options VALUE	54	0	0	54	0	0
Net unrealized gain (loss) on investments VALUE	0	0	0	0	0	0
Net unrealized gain (loss) on derivatives VALUE	0	0	0	0	0	0
Ending Balance VALUE at Mar. 31, 2012	$ 251,254	$ 313	$ 72	$ 598,474	$ (347,605)	$ 0
Ending Balance SHARES at Mar. 31, 2012		31,328,316	7,197,532