Statements of Shareholders’ Equity (Deficit) (USD $) In Thousands, unless otherwise specified	Total	Class A Common Stock	Class B Common Stock	Common Stock	Non- Voting Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings (Accumulated Deficit)
Balance at Dec. 31, 2010	$ (105,077)	$ 2	$ 1	$ 0	$ 0	$ 676	$ 0	$ (105,756)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of Class A & B common stock to common stock		(2)	(1)	3
Proceeds from initial public offering, net	170,828			1		170,827
Conversion of debt to common stock	279,206			2		279,204
Conversion of preferred stock to common stock	81,747			1		81,746
Record liability under Tax Receivable Agreement	(36,522)					(36,522)
Share-based compensation	530					530
Repurchase of common stock	(886)					(757)	(129)
Conversion of common stock to non-voting common stock	0			(1)	1
Proceeds from options exercised	423					423
Net income	76,448							76,448
Other	9					9
Balance at Dec. 31, 2011	466,706	0	0	6	1	496,136	(129)	(29,308)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	23,419							108,460
Balance at Mar. 31, 2012
Balance at Dec. 31, 2011	466,706					496,136	(129)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment to liability recorded under Tax Receivable Agreement	1,497					1,497
Share-based compensation	4,327					4,327
Repurchase of common stock	(1,022)						(1,022)
Proceeds from options exercised	469					469
Excess tax benefits from share-based compensation	2,098					2,098
Net income	108,460
Balance at Dec. 31, 2012	582,535	0	0	6	1	504,527	(1,151)	79,152
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment to liability recorded under Tax Receivable Agreement	2,336					2,336
Share-based compensation	5,689					5,689
Repurchase of common stock	(1,140)						(1,140)
Conversion of non-voting common stock to common stock	0			1	(1)
Proceeds from options exercised	852					852
Excess tax benefits from share-based compensation	1,927					1,927
Net income	176,918							176,918
Balance at Dec. 31, 2013	$ 769,117	$ 0	$ 0	$ 7	$ 0	$ 515,331	$ (2,291)	$ 256,070