Consolidated Statements of Changes in Stockholders' Equity Statement (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Total stockholders' equity	$ 402,249	$ 327,764	$ 402,249	$ 327,764	$ 253,196	$ 165,131
Common stock issued under stock plans and related tax effects (Shares)			1,428
Common stock issued under stock plans and related tax effects (Amount)			17,173	6,288	9,091
Stock-based compensation (Amount)			14,703	12,734	9,524
Stock-based retailer incentive compensation (Amount)			8,722	8,251	17,337
Conversion of Class B common stock by stockholders (Amount)			0	0	0
Net Income	1,036	10,370	34,040	47,219	52,083
Other Comprehensive Income (Loss), Net of Tax			(153)	76	30
Convertible Preferred Stock [Member]
Shares, Outstanding	0	0	0	0		0
Total stockholders' equity	7	7	7	7	7	0
Common stock issued under stock plans and related tax effects (Shares)			0	0	0
Common stock issued under stock plans and related tax effects (Amount)			0	0	0
Stock-based compensation (Shares)			0	0	0
Stock-based compensation (Amount)			0	0	0
Stock-based retailer incentive compensation (Shares)			0	0	0
Stock-based retailer incentive compensation (Amount)			0	0	0
Conversion of Class B common stock by stockholders (Shares)			0	0	(7)
Conversion of Class B common stock by stockholders (Amount)			0	0	(7)
Other Comprehensive Income (Loss), Net of Tax			0	0	0
Common Stock [Member] | Common Class A [Member]
Shares, Outstanding	37,729	31,798	37,729	31,798	30,162	14,762
Total stockholders' equity	38	31	38	31	30	13
Common stock issued under stock plans and related tax effects (Shares)			620	141	104
Common stock issued under stock plans and related tax effects (Amount)			1	0	2
Stock-based compensation (Shares)			0	0	0
Stock-based compensation (Amount)			0	0	0
Stock-based retailer incentive compensation (Shares)			0	0	0
Stock-based retailer incentive compensation (Amount)			0	0	0
Conversion of Class B common stock by stockholders (Shares)			(5,311)	(1,495)	(15,296)
Conversion of Class B common stock by stockholders (Amount)			(6)	(1)	(15)
Other Comprehensive Income (Loss), Net of Tax			0	0	0
Common Stock [Member] | Common Class B [Member]
Shares, Outstanding	0	4,197	0	4,197	5,280	27,091
Total stockholders' equity	0	4	0	4	5	27
Common stock issued under stock plans and related tax effects (Shares)			1,114	412	344
Common stock issued under stock plans and related tax effects (Amount)			2	0	0
Stock-based compensation (Shares)			0	0	0
Stock-based compensation (Amount)			0	0	0
Stock-based retailer incentive compensation (Shares)			0	0	0
Stock-based retailer incentive compensation (Amount)			0	0	0
Conversion of Class B common stock by stockholders (Shares)			(5,311)	(1,495)	(22,155)
Conversion of Class B common stock by stockholders (Amount)			(6)	(1)	(22)
Other Comprehensive Income (Loss), Net of Tax			0	0	0
Additional Paid-in Capital [Member]
Total stockholders' equity	199,251	158,656	199,251	158,656	131,383	95,433
Common stock issued under stock plans and related tax effects (Amount)			17,170	6,288	9,089
Stock-based compensation (Amount)			14,703	12,734	9,524
Stock-based retailer incentive compensation (Amount)			8,722	8,251	17,337
Conversion of Class B common stock by stockholders (Amount)			0	0	0
Other Comprehensive Income (Loss), Net of Tax			0	0	0
Retained Earnings [Member]
Total stockholders' equity	203,000	168,960	203,000	168,960	121,741	69,658
Common stock issued under stock plans and related tax effects (Amount)				0	0
Stock-based compensation (Amount)				0	0
Stock-based retailer incentive compensation (Amount)				0	0
Conversion of Class B common stock by stockholders (Amount)			0	0	0
Net Income				47,219	52,083
Other Comprehensive Income (Loss), Net of Tax			0	0	0
Accumulated Other Comprehensive Income (Loss) [Member]
Total stockholders' equity	(47)	106	(47)	106	30	0
Common stock issued under stock plans and related tax effects (Amount)				0	0
Stock-based compensation (Amount)				0	0
Stock-based retailer incentive compensation (Amount)				0	0
Conversion of Class B common stock by stockholders (Amount)				0	0
Other Comprehensive Income (Loss), Net of Tax			$ (153)	$ 76	$ 30