CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Non-Controlling Interest [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balances at Dec. 31, 2009	$ 2	$ 103,684	$ 26,660	$ 0	$ (1,248)	$ 129,098
Balances (in shares) at Dec. 31, 2009	17,917,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	28,383	(181)	0	28,202
Foreign currency translation adjustment	0	0	0	0	(1,262)	(1,262)
Contributions from non-controlling interest	0	0	0	18,256	0	18,256
Issuance of common stock, net of underwriting discount and offering expenses	0	22,353	0	0	0	22,353
Issuance of common stock, net of underwriting discount and offering expenses (in shares)	1,381,000
Payment of income tax withheld on vested restricted stock	0	(42)	0	0	0	(42)
Payment of income tax withheld on vested restricted stock (in shares)	(3,000)
Stock based compensation	0	1,069	0	0	0	1,069
Balances at Dec. 31, 2010	2	127,064	55,043	18,075	(2,510)	197,674
Balances (in shares) at Dec. 31, 2010	19,295,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	50,189	625	0	50,814
Foreign currency translation adjustment	0	0	0	0	(871)	(871)
Stock based compensation	0	1,119	0	0	0	1,119
Balances at Dec. 31, 2011	2	128,183	105,232	18,700	(3,381)	248,736
Balances (in shares) at Dec. 31, 2011	19,295,000					19,295,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	0	0	63,465	816	0	64,281
Foreign currency translation adjustment	0	0	0	0	464	464
Deconsolidation of non-controlling interest	0	49	0	(19,516)	0	(19,467)
Issuance of common stock, net of underwriting discount and offering expenses	0	51,543	0	0	0	51,543
Issuance of common stock, net of underwriting discount and offering expenses (in shares)	2,757,000					2,757,170
Stock based compensation	0	1,288	0	0	0	1,288
Balances at Dec. 31, 2012	$ 2	$ 181,063	$ 168,697	$ 0	$ (2,917)	$ 346,845
Balances (in shares) at Dec. 31, 2012	22,052,000					22,052,529