CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (USD $)	Total USD ($)	Class B	Common Stock USD ($)	Additional Paid-In Capital USD ($)	Accumulated Deficit USD ($)
Balance at Dec. 23, 2010
Increase (Decrease) in Stockholders' Equity
Sale of common stock, net of underwriting discounts and offering costs of $14,121,680	$ 356,542,135
Contribution of capital	356,542,135		29,123	356,513,012
Contribution of capital (in shares)		7,500	29,122,521
Net income (loss)	(161,726)
Balance at Dec. 31, 2010	356,380,409		29,123	356,513,012
Balance (in shares) at Dec. 31, 2010		7,500	29,122,521
Balance at Dec. 25, 2010
Increase (Decrease) in Stockholders' Equity
Issuance of Class B common stock (in shares)			29,122,521
Sale of common stock, net of underwriting discounts and offering costs of $14,121,680			29,123	356,513,012
Sale of common stock, net of underwriting discounts and offering costs of $14,121,680 (in shares)			29,122,521
Net income (loss)					(161,726)
Balance at Dec. 31, 2010	356,380,409		29,123	356,513,012	(161,726)
Balance (in shares) at Dec. 31, 2010		7,500	29,122,521
Increase (Decrease) in Stockholders' Equity
Issuance of common stock to directors for services	167,500			167,500
Issuance of Class B common stock (in shares)	10,000,000	4,600	10,000,000
Forfeiture of Class B common stock (in shares)		(2,100)
Sale of common stock, net of underwriting discounts and offering costs of $14,121,680	155,878,320		10,000	155,868,320
Sale of common stock, net of underwriting discounts and offering costs of $14,121,680 (in shares)	10,000,000	4,600	10,000,000
Exchange of Class B common stock for issuance of restricted common stock to officers and employees	438		438
Exchange of Class B common stock for issuance of restricted common stock to officers and employees (in shares)		(10,000)	437,787
Restricted stock used for tax withholdings	(1,405,188)		(83)	(1,405,105)
Restricted stock used for tax withholdings (in shares)			(82,724)
Stock-based compensation	4,268,856			4,268,856
Net income (loss)	12,691,181				12,691,181
Balance at Dec. 31, 2011	527,981,516		39,478	515,412,583	12,529,455
Balance (in shares) at Dec. 31, 2011	39,477,584		39,477,584
Increase (Decrease) in Stockholders' Equity
Restricted common stock issued	736		736
Restricted common stock issued (in shares)			736,780
Restricted common stock forfeited	(80)		(80)
Restricted common stock forfeited (in shares)			(80,338)
Restricted stock used for tax withholdings	(466,904)		(18)	(466,886)
Restricted stock used for tax withholdings (in shares)			(18,490)
Offering costs related to sale of common stock	(2,952)			(2,952)
Stock-based compensation	4,482,611			4,482,611
Net income (loss)	46,522,577				46,522,577
Balance at Dec. 31, 2012	$ 578,517,504		$ 40,116	$ 519,425,356	$ 59,052,032
Balance (in shares) at Dec. 31, 2012	40,115,536		40,115,536